Oil Change Interval

withee1319 · March 1, 2020

Oil change interval question. I have had an LB7, LLY, LMM, and now the 2020 L5P. All my other duramax trucks had an oil change interval around 10,000 miles. Why did they drop it to what appears to be around 5000 accordingto my OLM? Could it be emissions dumping more crap back in the engines?

I asked this on another page and got no answers just obvious questions. Yes I have OLM, and it's on track for 5000 miles to 0%. Book says 7500. All my other duramax engines were around 10% drop per thousand miles. That ended up at around 10,000 mile oil changes. Fuel filter life seems to be averaging about the same as my LMM.

I ran an oil sample several years ago on my LLY at 10,000. Results said run another 10,000 after a filter only change. Also my buddy has a 18 Ram and his OLM has him changing oil at 12,000.

So the question is why is the oil life interval shrinking? Technology is better and oils are better. Just curious. Thanks,

redwngr · March 1, 2020

37 minutes ago, withee1319 said:

Oil change interval question. I have had an LB7, LLY, LMM, and now the 2020 L5P. All my other duramax trucks had an oil change interval around 10,000 miles. Why did they drop it to what appears to be around 5000 accordingto my OLM? Could it be emissions dumping more crap back in the engines?

I asked this on another page and got no answers just obvious questions. Yes I have OLM, and it's on track for 5000 miles to 0%. Book says 7500. All my other duramax engines were around 10% drop per thousand miles. That ended up at around 10,000 mile oil changes. Fuel filter life seems to be averaging about the same as my LMM.

I ran an oil sample several years ago on my LLY at 10,000. Results said run another 10,000 after a filter only change. Also my buddy has a 18 Ram and his OLM has him changing oil at 12,000.

So the question is why is the oil life interval shrinking? Technology is better and oils are better. Just curious. Thanks,

I think they've added the 'time' interval to the calculation so that it matches the max recommended calendar time from the maint schedule.

Some low mileage owners used to comment wonder why they were at or beyond the recommended 'time' in manual but the OLM still wasn't close to zero.

Any chance you truck only runs 5000 mile/year?

(they recommend changing oil/filter once per year, and resetting OLM, even if the OLM hasn't reached zero)

withee1319 · March 1, 2020

I bought it the end of November and have 1500 miles on it. So not high mileage (yet).

redwngr · March 1, 2020

1 hour ago, withee1319 said:

I bought it the end of November and have 1500 miles on it. So not high mileage (yet).

Do you know when it was built?

Grumpy Bear · March 1, 2020

Brother I don't normally reply on the diesel pages but looks like your not getting anywhere. An opinion is the best I can do so here goes.

When marketing people convince the public that something is 'better' as in better oils, you're no getting the whole story. Fact is it can be down right deceiving. There are three ways to make oil 'better' and all of them depend a great deal on the previous point of reference.

1.) They can narrow the variation in the liquid chain length and alter the branching. Done and done to death until there is no more low hanging fruit on that tree.

2.) Improve the additive package. WAS the most common method

3.) Make it cleaner.

The problem with the newest oils is that they are literally a step backward in SAE classification specification specs. They have drastically reduced the phosphate levels in ZDDP packages. These packages do triple duty. They are not just EP additives but corrosion and detergent as well. They have reduces calcium loading to help with LSPI which is also a detergent as well as an acid neutral additive. They used these additives for years because they are the MOST effective for the jobs they are asked to do. They are replaced, in part, with LESS effective additives. These additives do not exist in a vacuum chemically. They are synergies. SO when an oil company says 'BETTER" oil they mean better at LSPI prevention. Better at not poisoning cat converters and O2 sensors. NOT better at protecting you motor. Did they lie? I'll leave that up to you.

Okay the OEM's are just as problematic. They overestimate themselves and their equipment often to gain a marketing edge. Or at least the perception of one. 7,500 OCI's hasn't worked out so well for AFM motors and so they crawfish it back along with shorter warranty miles. I honestly don't know all the issues of modern diesels so offering the preceding in example and opinion. ONLY

It's more help that you were getting. Your welcome.

Colossus · March 1, 2020

Yes. And now you have idiots designing these things who think that transmission fluid is safe to run to 100,000 or to never change, and the public believes it because its what the manufacturer said yet common sense says otherwise.

diyer2 · March 1, 2020

My 2 cents.

The question to me is not about oil life monitors shrinking.

The question is:

Whats the best for the motor? If you drink the Kool-Aide they say they have oils that will go 20 K miles.

If you want to keep your engine happy IMO you change more frequently than an OLM says. You can look on the net and find lots of opinions.

If you use a high quality 100% synthetic oil such as Amsoil and a high quality oil filter I might consider going 7500. No longer.

If you use of the shelf oil of any brand and a good quality oil filter, I wouldn't go over 5 k miles.

Your prevoius oil changes were done at 10 K miles you say. What oil and filter did you use? So why question it now?

My grandpa used to say " Why worry about something that may not happen"

What I would do is do what makes you happy.

KARNUT · March 1, 2020

I really don’t want to start the whole extended debate again. Back when I was driving diesel trucks it took almost 3 gallons per change. Every 5K miles that’s a lot of money.

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withee1319 · March 1, 2020

So the 10,000 mile oil changes were amsoil with amsoil filters. I question it now because of warranty. And before the 10,000 was inline with my OLM. My LMM has 297000 on it without a hiccup. I agree with the comment above 100,000 on a tranny oil change is stupid.

So amsoil and filter is around $100 doing it yourself. So yeah it gets a little pricey. Over the road trucks arent changing oil that quick.

BTW my background is a diesel mechanic. Just wandering if anyone knew why GM shortened oil life expectancy when other manufacturers have not. Thanks.

Grumpy Bear · March 2, 2020

4 hours ago, KARNUT said:

I really don’t want to start the whole extended debate again. Back when I was driving diesel trucks it took almost 3 gallons per change. Every 5K miles that’s a lot of money.

No debate required. Explanation perhaps. Three gallons is allot of oil. Or should I say allot of dilution and allot of detergent. No need for a 5K of your holding that much oil in the sump. You had a swimming pool for a sump.

If people change oil by an ISO 4406 cleanliness codes instead of the TBN you would see a shift in both filtration and OCI length. IMHO of course.

Colossus · March 2, 2020

The oils can go the distance, it's the filters that need to be changed 5000-10,000 miles.

Grumpy Bear · March 2, 2020

8 hours ago, Colossus said:

The oils can go the distance, it's the filters that need to be changed 5000-10,000 miles.

If they stay clean and are not contaminated. The more I look into filtration the more fascinating that becomes. :thumbs:

Edited March 2, 2020 by Grumpy Bear

Colossus · March 3, 2020

The engine is always wearing, which means metals (and the plastics in the engine now a days) are shaving/grinding off, and dirt and such do get past everything and you get build up. No getting around it.

Grumpy Bear · March 3, 2020

14 hours ago, Colossus said:

The engine is always wearing, which means metals (and the plastics in the engine now a days) are shaving/grinding off, and dirt and such do get past everything and you get build up. No getting around it.

Yes it is going to wear and eventually wear out. That is a given and we can't change that. What we can change is the rate it happens at.

I have this Harley TC88. An early one with the phenolic cam chain tensioners. Ask anyone you like with experience with these and they will tell you 30K miles is there limit. Some don't make it that long and when the phenolic wears away the steel shoe below it gets chewed to shrapnel and destroys the bottom end in minutes.

Using the products and procedures I used from day one with this motor the ones we pulled out of her at 48K would have gone 150 K. Over 85% of the shoe remaining.