OCI, not when but why?

[Grumpy Bear]

On 6/28/2026 at 8:49 AM, Atlas said:

Here's the tie-in to this thread. If an oil sample tests shows a wear indicator of 7 using cheaper ACDelco oil, and a wear indicator of 2 (lower = less wear) using a particular brand of Mobil oil, and wear has a linear relationship with engine lifespan, anyone could assume that Mobil is reducing wear by more than 50% (let's just say a 200% reduction for you red state people trying hard to do math) which leads to increasing engine life by 2x. Perhaps, in a vacuum, by itself, when dreamed by AI.

 

 

The filtering to wear relationship goes like this: 

 

 

'Relative Engine Life "Factor" new divided by the factor old. So 8/3= 2.67. That result is the multiplier thus if a motor had an effective life of 100K using a filter with a 45 micron rating at a Beta ratio of 75 then a filter with a micron rating of 10 at a Beta of 75 would improve expected engine life to 267,000 miles. 

 

Wear metals are an indirect indicator. Less is better and the motor lives longer but there isn't a multiplier like there is for filtration so well documented. Most of that has to do with the sensitivity of the wear metals tests themselves. They read a 'slice' of the spectrum but not the absolute values for the entire spectrum. So a general indicator that is used WITH the results of other tests. Two others considered in this post. Trending is very important. 

 

There is also the influence of corrosive wear which may be seen in the wear metals but separate from load based or viscosity mitigated indication. It's a small graph but the gray line is wear vs the TBN/TAN crossover. Not as useful as it used to be as there are now new chemistries for acid remediation that don't show up in standard UAO testing. They will catch up or be found liars. Only two possible outcomes, eh? 

 

 

 

 

 

 

Edited July 14 by Grumpy Bear

[Atlas]

13 hours ago, Grumpy Bear said:

 

 

The filtering to wear relationship goes like this: 

 

 

'Relative Engine Life "Factor" new divided by the factor old. So 8/3= 2.67. That result is the multiplier thus if a motor had an effective life of 100K using a filter with a 45 micron rating at a Beta ratio of 75 then a filter with a micron rating of 10 at a Beta of 75 would improve expected engine life to 267,000 miles. 

 

Wear metals are an indirect indicator. Less is better and the motor lives longer but there isn't a multiplier like there is for filtration so well documented. Most of that has to do with the sensitivity of the wear metals tests themselves. They read a 'slice' of the spectrum but not the absolute values for the entire spectrum. So a general indicator that is used WITH the results of other tests. Two others considered in this post. Trending is very important. 

 

There is also the influence of corrosive wear which may be seen in the wear metals but separate from load based or viscosity mitigated indication. It's a small graph but the gray line is wear vs the TBN/TAN crossover. Not as useful as it used to be as there are now new chemistries for acid remediation that don't show up in standard UAO testing. They will catch up or be found liars. Only two possible outcomes, eh? 

 

 

 

 

 

 

 

Are we talking about the same thing, though? The 7 versus 3 wear metals was from Lakespeed's 3.0-specific oil brand comparison test between AcDelco oil and Mobil ESP. The filter remains a constant so whatever excess particles the AcDelco oil is producing aren't being filtered out.

 

I'm assuming there's a parallel comparison to be made; IF the filter can filter down those particles, engine life increases, and your graph makes the case that a better filter (lower micron rating) can increase engine life. Introducing fewer particles AND filtering those particles with higher efficiency is the best of all worlds. Good oil, good filter.

 

Where we may disagree is the "baseline relative engine life". I'm more apt to believe the base engine life value is 200k+ on very average oil and filters, "bulk oil of unknown brand and white-label generic fleet-grade filter, Jiffy Lube"

 

Going from a 10 micron filter to a 5 micron filter should boost a base 200k to 275k in a vacuum as a single factor alone.

 

Here's the whatabout: How does regularly changing the oil and filter ahead of recommended schedule influence baseline engine life? Most people aren't going to science the heck out of this stuff or ask about Micron ratings, HTHS, or wear comparison tests at Jiffy Lube. Most of the Jiffy lube techs would say they need to call their tech support line to even try to get an answer.

 

--

 

Because we love anecdotes here, when I was fishing for 4.3 parts at a local yard this weekend, ALL of the 4.3 vehicles had well over 200k. I love looking at odometers of junked vehicles. How far did THIS go before landing at the crusher? The ones that still had engines weren't seized. None of them were vehicles I'd consider were Amsoil queens, in fact most of them had some kind of service cling-sticker in the corner of the windshield indicating it probably had very average maintenance services. Even the fresh parts rigs- I'm not sure taking an S/T series to 400k has much value considering the running value of those vehicles was probably somewhere around $1,000. 25+ years is a good run on time alone.

 

The intake manifold I salvaged had clean and bright pool areas. As expected, I found the fuel lines in the manifold rubbed through, just like mine. I'm guessing the lines on that donor truck started leaking, the truck started running rough, and its owner said that's enough I'm unwilling or can't take it out of service for several days, or spend $1000+ to repair it at a shop, it's simply time for a newer more reliable vehicle (or, more than likely, this is the 2nd, 3rd time this has happened in the truck's lifetime). While I don't count on my Blazer for reliability, the thought of giving it away for parts at certain points during my adventure, and being mentally free from its needs has has crossed my mind. I'd be losing $1500 or so, but I can only make more money; not time.

Edited July 14 by Atlas

[KARNUT]

26 minutes ago, Atlas said:

 

Are we talking about the same thing, though? The 7 versus 3 wear metals was from Lakespeed's 3.0-specific oil brand comparison test between AcDelco oil and Mobil ESP. The filter remains a constant so whatever excess particles the AcDelco oil is producing aren't being filtered out.

 

I'm assuming there's a parallel comparison to be made; IF the filter can filter down those particles, engine life increases, and your graph makes the case that a better filter (lower micron rating) can increase engine life. Introducing fewer particles AND filtering those particles with higher efficiency is the best of all worlds. Good oil, good filter.

 

Where we may disagree is the "baseline relative engine life". I'm more apt to believe the base engine life value is 200k+ on very average oil and filters, "bulk oil of unknown brand and white-label generic fleet-grade filter, Jiffy Lube"

 

Going from a 10 micron filter to a 5 micron filter should boost a base 200k to 275k in a vacuum as a single factor alone.

 

Here's the whatabout: How does regularly changing the oil and filter ahead of recommended schedule influence baseline engine life? Most people aren't going to science the heck out of this stuff or ask about Micron ratings, HTHS, or wear comparison tests at Jiffy Lube. Most of the Jiffy lube techs would say they need to call their tech support line to even try to get an answer.

 

--

 

Because we love anecdotes here, when I was fishing for 4.3 parts at a local yard this weekend, ALL of the 4.3 vehicles had well over 200k. I love looking at odometers of junked vehicles. How far did THIS go before landing at the crusher? The ones that still had engines weren't seized. None of them were vehicles I'd consider were Amsoil queens, in fact most of them had some kind of service cling-sticker in the corner of the windshield indicating it probably had very average maintenance services. Even the fresh parts rigs- I'm not sure taking an S/T series to 400k has much value considering the running value of those vehicles was probably somewhere around $1,000. 25+ years is a good run on time alone.

 

The intake manifold I salvaged had clean and bright pool areas. As expected, I found the fuel lines in the manifold rubbed through, just like mine. I'm guessing the lines on that donor truck started leaking, the truck started running rough, and its owner said that's enough I'm unwilling or can't take it out of service for several days, or spend $1000+ to repair it at a shop, it's simply time for a newer more reliable vehicle (or, more than likely, this is the 2nd, 3rd time this has happened in the truck's lifetime). While I don't count on my Blazer for reliability, the thought of giving it away for parts at certain points during my adventure, and being mentally free from its needs has has crossed my mind. I'd be losing $1500 or so, but I can only make more money; not time.

For some unexplained reason my father wanted a salvage yard. As we were getting the family business off the ground one brother ran the salvage yard. We gathered there when rained out working on pipelines in the eighties to pull parts. Perfectly good running vehicles would come to us simply because they wouldn’t pass emissions inspection. We were able to swap parts and sell some of them. I got a clean old nova with a bad engine. I pulled a perfectly good small block out a Camaro. A father and son project with a rebuilt engine. The son couldn’t get the engine running right. The problem was the spark plugs weren’t gapped. The 90s vehicles probably widened the gap of shade tree do it yourself engine repair. My do it yourself hot rod repair stopped at the 70s. After that my trusted mechanic kept them in running shape. 

[Grumpy Bear]

1 hour ago, Atlas said:

 

Are we talking about the same thing, though? The 7 versus 3 wear metals was from Lakespeed's 3.0-specific oil brand comparison test between AcDelco oil and Mobil ESP. The filter remains a constant so whatever excess particles the AcDelco oil is producing aren't being filtered out.

 

I'm assuming there's a parallel comparison to be made; IF the filter can filter down those particles, engine life increases, and your graph makes the case that a better filter (lower micron rating) can increase engine life. Introducing fewer particles AND filtering those particles with higher efficiency is the best of all worlds. Good oil, good filter.

 

Where we may disagree is the "baseline relative engine life". I'm more apt to believe the base engine life value is 200k+ on very average oil and filters, "bulk oil of unknown brand and white-label generic fleet-grade filter, Jiffy Lube"

 

Going from a 10 micron filter to a 5 micron filter should boost a base 200k to 275k in a vacuum as a single factor alone.

 

Here's the whatabout: How does regularly changing the oil and filter ahead of recommended schedule influence baseline engine life? Most people aren't going to science the heck out of this stuff or ask about Micron ratings, HTHS, or wear comparison tests at Jiffy Lube. Most of the Jiffy lube techs would say they need to call their tech support line to even try to get an answer.

 

--

 

Because we love anecdotes here, when I was fishing for 4.3 parts at a local yard this weekend, ALL of the 4.3 vehicles had well over 200k. I love looking at odometers of junked vehicles. How far did THIS go before landing at the crusher? The ones that still had engines weren't seized. None of them were vehicles I'd consider were Amsoil queens, in fact most of them had some kind of service cling-sticker in the corner of the windshield indicating it probably had very average maintenance services. Even the fresh parts rigs- I'm not sure taking an S/T series to 400k has much value considering the running value of those vehicles was probably somewhere around $1,000. 25+ years is a good run on time alone.

 

The intake manifold I salvaged had clean and bright pool areas. As expected, I found the fuel lines in the manifold rubbed through, just like mine. I'm guessing the lines on that donor truck started leaking, the truck started running rough, and its owner said that's enough I'm unwilling or can't take it out of service for several days, or spend $1000+ to repair it at a shop, it's simply time for a newer more reliable vehicle (or, more than likely, this is the 2nd, 3rd time this has happened in the truck's lifetime). While I don't count on my Blazer for reliability, the thought of giving it away for parts at certain points during my adventure, and being mentally free from its needs has has crossed my mind. I'd be losing $1500 or so, but I can only make more money; not time.

 

Unless you are using a bypass filer system with a Beta of 1000 at 2 micron the commercial filters we have access to, even the very best of them, are poor at the 5 to 10 micron range the typical UOA test can 'see'. Point is there are some truly awful filters being sold A 45 micron Beta 75 filter is what Dyson used to call a screen door on a submarine. That leaves wear metals disconnected from filtration unless particulates are larger than the test can 'see' and yet captured by the filter...which is its job. If that is true then you have a major issue screaming at you. 

 

The graph isn't mine. It belongs to GM and their study on this area. I looked up those studies and provided those SAE tech paper addresses multiple times. Machinery Lubrication displayed it and confirmed it. So if you have doubts about the study you'll have to take it up with GM Engineering. Just like you would have to take up a difference in opinion about the meaning a word with Webster or the length of on inch with the National Institute of Standards and Technology. 

 

1 hour ago, Atlas said:

How does regularly changing the oil and filter ahead of recommended schedule influence baseline engine life?

 

Most manuals have two schedules. "Normal Service" and "Severe Service". On it's face it tells you that oil in severe service is more highly stressed and doesn't "Last as Long". The item to bore in on is LAST...what does that mean? 

 

It's the same question one asks about how long to toast bread. What are the inputs? Bread type? Wattage of the toaster? Distance from the elements? What is your preferred level of done? 

 

So lets paint this with a broader brush. Oil is made up of the base and the additive package. The first is altered by heat and oxygen and later is sacrificial with a finite life subject to inputs toward that end. Resistance and supply. 

 

It is the reason an OEM's OCI's are determined by 1.) the specifications of the recommended lubricant and 2.) risk management toward the bottom line. Those lubricants are also subject to cost effectiveness for the OEM. 

 

There is a tendency for most people to believe that the OEM recommended oil rest on the top shelf and that anything other is lesser than. Truth is there are more oils on higher shelves than those on the lower shelf below the OEM's. They make that choice on COST TO THE OEM. Testing is incidental to the margin. 

 

GM makes MONEY, the car/truck is a TOOL to leverage MONEY. Insert whatever car brand you like. Until you forking over a million plus COST not quality is the driver. Thus it is by DESIGN the recommended OCI's and oils fall well short of 'best practice protections'. Proof isn't hard to find. GM Ecotec I-4 2400 breather system and cold start PCM tuning has killed more motors and resulted in more litigation for those that used the 'recommended' practice than GM could bear. What was their response? SHORTEN THE OCI. TWICE. 

 

I don't know how long to leave oil in an I don't know how the oil will respond to MY circumstances and because I don't and can't blanket statement or anecdotal evidence my way out of it.....I TEST and FIND the right OCI for the oil I CHOOSE. There is no shortcut but there is blind allegiance. I don't blindly trust anything. 

 

People hear the word 'detergent' and believe that in the context of oil it means the same thing as laundry soap... Only in the most rudimentary way. It's the first additive to give up on you and they are putting less and less with each new API standard. Solvency can be used but it cost. Some unique undisclosed chemistries can be used. Valvoline R & P in example. OEM's haven't an interest in anything they see as limiting market participation. Whatever. 

 

 

 

 

Edited July 14 by Grumpy Bear

[diyer2]

I'm an advocate for K.I.S.S. A quality oil like Amsoil and shorter OCI"s works for me.

[Grumpy Bear]

In their own words: 

 

https://blog.amsoil.com/how-engine-sludge-forms-and-how-to-prevent-it-2/

 

[Quote]

Synthetic Oil Helps Prevent Sludge

Fortunately, sludge and varnish deposits are something that can be controlled. Using thermally stable synthetic base oils reduces the rate of degradation (oxidation).

 

Antioxidant additives further help reduce the rate of degradation. One of the most widely used is zinc dithiophosphate. Not only is it an excellent oxidation inhibitor, but it is also an outstanding anti-wear additive.

 

High-Quality Additives Fight Sludge

Fortunately, it is possible to address many of the issues that occur after the initial oxidation stage. Additives, such as detergents and dispersants, help promote the suspension of contaminants within the oil and keep them from agglomerating.

 

Detergents, which are also alkaline in nature, assist in neutralizing acids generated in the sludge-building process. Antioxidant, dispersant and detergent additives are consumed during use.

 

To achieve maximum life expectancy, use a motor oil with high concentrations of antioxidant, dispersant and detergent additives.  [End Quote]

 

So quality base oil and then the last sentence above. TBN and ZDP levels matter. The one thing not covered was sufficient viscosity. Sad.  

 

And yet we now have since API SN lower amount of them all with the only real change being a slight up tick in base oil selection. Along with lower concentrations of everything that makes oil work and lower and lower viscosity there is still an insistence on longer OCI's. 

 

How low does the peanut butter and jelly level have to get before we say it's just white bread folded? 

 

The new smoke and mirror treatment is the 'additives are INVISIBLE' to UOA testing with a health dose of TRUST ME. 

 

I'm not picking on AMSOIL. This is coming from all of them. Every last one of them that abandon the low wear model in favor of the high mpg/EPA compliance model. 

Edited 12 hours ago by Grumpy Bear

[Chuck FB]

It definitely seems quite evident that emissions and fuel economy targets rule above the best case scenario of what the engines best health and life could be otherwise. Items like DI and turbo DI engines with their LSPI issues as well as cats being reduced in life if the proper levels of certain additives were allowed to be utilized and so something has to be compromised and as you point out that is the engine protection from sludge, acid and wear which isn't in the manufactures best interest regardless to worry about in this race to profits from higher sales and so if the engines wear out sooner the next sale is closer at hand. 

 

I am hearing that its likely the two new 2027 GM half ton truck engines will call for a 0W-30 oil, now if that is an existing oil I would have to think so but we will see in the coming months. Sadly as you've pointed out to me, over the last number of years the push has been on to reduce the actual operating temperature viscosity within each designated viscosity grade so that 11.5 to 12 range for a 30 weight for example is more in that just above 10 range at 100c along with that temporary viscosity sheer dropping it even further down as per that "energy conserving" designation, not to mention how some oils are not as sheer stable as would be ideal and that mixed with a long OCI paints a picture with a little too much glitter shall we say !. 

 

All that and the warranty gods scaring the vehicle owner into sticking with that watery wine or risk loosing their warranty coverage if they go and use an oil that is of a higher viscosity even if it meets the emissions and LSPI requirements and would never damage the engine but may very well allow for an engines longer life depending on engine use scenarios ... high ambient temps, towing etc that push oils to their limits.

[diyer2]

I did shorter OCI"s for many years without an issue, fights sludge and wear IMO. Recently started using Amsoil, will not do the recommended/advertised miles between changes. 

[Grumpy Bear]

2 hours ago, Chuck FB said:

It definitely seems quite evident that emissions and fuel economy targets rule above the best case scenario of what the engines best health and life could be otherwise. Items like DI and turbo DI engines with their LSPI issues as well as cats being reduced in life if the proper levels of certain additives were allowed to be utilized and so something has to be compromised and as you point out that is the engine protection from sludge, acid and wear which isn't in the manufactures best interest regardless to worry about in this race to profits from higher sales and so if the engines wear out sooner the next sale is closer at hand. 

 

Sad thing is that this doesn't have to be the case. LSPI can be solved without a reduction in TBN. Swap Ca for Mg. 

Cats are not a issue if the OEM can get a ring and valve guide seal even at SN levels of SAPS. Dizzy is purring like a kitten with a bowl of warm milk. 200K of Full SAPS oil and zero detonation issues and nice a clean inside and out. This shouldn't be an issue. It isn't 1920. 

 

Tell ya what AMSOIL SS is excellent at, internal cleanliness. The new formula is even a step up from their already outstanding cleanliness levels. Can't say the OEM offering is quite that clean. There marketing suggest the SS is cleaner.

 

2 hours ago, diyer2 said:

I did shorter OCI"s for many years without an issue, fights sludge and wear IMO. Recently started using Amsoil, will not do the recommended/advertised miles between changes.

 

That is the only defense with at shelf oil. Nothing wrong with them if you ignore the marketing and OEM 'recommended' OCI and use a thimble full of common sense.  You go sir. 

[PunchT37]

Hmm. A real reason to not just use the odometer to determine OCI?

 

 

[Chuck FB]

1 hour ago, Grumpy Bear said:

 

Sad thing is that this doesn't have to be the case. LSPI can be solved without a reduction in TBN. Swap Ca for Mg. 

Cats are not a issue if the OEM can get a ring and valve guide seal even at SN levels of SAPS. Dizzy is purring like a kitten with a bowl of warm milk. 200K of Full SAPS oil and zero detonation issues and nice a clean inside and out. This shouldn't be an issue. It isn't 1920. 

 

Tell ya what AMSOIL SS is excellent at, internal cleanliness. The new formula is even a step up from their already outstanding cleanliness levels. Can't say the OEM offering is quite that clean. There marketing suggest the SS is cleaner.

 

 

That is the only defense with at shelf oil. Nothing wrong with them if you ignore the marketing and OEM 'recommended' OCI and use a thimble full of common sense.  You go sir. 

 

That's interesting, I assume that would add to the cost of the oil but also I was forgetting to bring up the issue of the low tension rings allowing more oil past which in turn forces the cats to have more oil additives pass through them that wouldn't otherwise so they are creating that problem and of course its all in the name of fuel economy. Mind you the other issue would be the lack of additives that fight the formation of carbon within the piston ring grooves which turn the engine into an oil burner and with in this GM forums case is your average off the shelf Dexos licensed oil, meanwhile the other off the shelf oil being Valvoline's R&P isn't licensed and the only one that is which is that certain Mobil oil that came out recently ( its not even being marketed in Canada ) and only a fraction of vehicle owners are going to be using it out of all the other oils on the shelf or the quickie lube bay that meet the Dexos spec by way of actual licensing. 

 

Also I suspect that its an easy excuse to pool the non turbo DI engines in with the turbo DI engines and design the oil to not have LSPI issues in the most demanding engines and short change the naturally aspirated DI by not offering a higher concentration of additive package they could handle and still not be at risk of LSPI. 

 

I wonder if Amsoil flipped the switch just lately and did whatever packaging designation at the same time as I wonder what oil formulation I would have bought in May, of course I don't know when it was packaged at the factory vs how long it was in storage at the Edmonton warehouse. I know its been said at least in the past that the big players switch over to a reformulated oil but the packaging has not changed until they make that move as well so there is that cross over time where its a new formulation in a predated formula marked package. 

[Grumpy Bear]

1 hour ago, PunchT37 said:

Hmm. A real reason to not just use the odometer to determine OCI?

 

 

That dog don't hunt. 

 

First, a 2025 with 12K on the clock AND idled for a year nonstop is false on it's face; this is 2026. You can do one or the other but not both. 

 

Second, ENGINE HOURS are absolutely available. The rest is third grade math. Micky Mouse scanner he got out of a box of Cracker Jacks OR an ID10T error. 

 

Third, if they ran it out of oil "Several times" that motor is boned on the first hit. 

 

Does this guy think piling higher makes it stink less? 

[PunchT37]

3 minutes ago, Grumpy Bear said:

 

That dog don't hunt. 

 

First, a 2025 with 12K on the clock AND idled for a year nonstop is false on it's face; this is 2026. You can do one or the other but not both. 

 

Second, ENGINE HOURS are absolutely available. The rest is third grade math. Micky Mouse scanner he got out of a box of Cracker Jacks OR an ID10T error. 

 

Third, if they ran it out of oil "Several times" that motor is boned on the first hit. 

 

Does this guy think piling higher makes it stink less? 

I agree. That`s a LOT of sludge for 12,000 miles. I tossed that out here since this is an OCI thread. There`s tons of people here that do not post.

 

I used to work on a city fleet. That includes police cars and fire trucks. Lesson is, not to only use the odo for oci. A police car has a ton of hours on the engine for the miles it shows. And, not just idling, directing traffic. They beat on these things.

 

Course, since it is a Kia, they were gonna use the "100,000 mile warranty" for their OCI.

[Chuck FB]

28 minutes ago, Grumpy Bear said:

 

That dog don't hunt. 

 

First, a 2025 with 12K on the clock AND idled for a year nonstop is false on it's face; this is 2026. You can do one or the other but not both. 

 

Second, ENGINE HOURS are absolutely available. The rest is third grade math. Micky Mouse scanner he got out of a box of Cracker Jacks OR an ID10T error. 

 

Third, if they ran it out of oil "Several times" that motor is boned on the first hit. 

 

Does this guy think piling higher makes it stink less? 

 

I'm not sure what to say on that mess but I will say that is an odd thing for that mechanic to speculate on as per assuming its been run out of oil a few times as the odds of that engine having instead piled up with a complete seizure would be very high if such events had actually taken place. However there is nothing saying that the oil has ever been changed although once again, what filter was on that engine as that would tell part of the story if its possible to figure out if its a factory installed filter or not. Too many items unknown and a lot of speculation, but regardless of that its one fubared mess that is mind boggling to see for a vehicle that new and its hard to imagine how it ever made it that far in life looking at the top of the engine. 

 

His scanners, I've watched him before here and there and I'd have to say if I recall correctly that some of his scanning equipment is one or two steps up from a child's Exo Sketch 

[Chuck FB]

30 minutes ago, PunchT37 said:

I agree. That`s a LOT of sludge for 12,000 miles. I tossed that out here since this is an OCI thread. There`s tons of people here that do not post.

 

I used to work on a city fleet. That includes police cars and fire trucks. Lesson is, not to only use the odo for oci. A police car has a ton of hours on the engine for the miles it shows. And, not just idling, directing traffic. They beat on these things.

 

Course, since it is a Kia, they were gonna use the "100,000 mile warranty" for their OCI.

 

I don't know how far back vehicles had hour meters, be it driver accessible or diag accessible but was wondering if there was any rule of thumb your shop came up with in regards to an hour limit on engine oil regardless of the miles on the oil. 

 

I know with construction or farm equipment its almost always based on engine hours for maintenance scheduling as no other metric really applies other than a seasonal time limit that one self imposes on items like engine oil.