Oil Life Monitor - Predicting Oil Life Remaining after X Miles Driven

Probity · July 1, 2024

Lots of "interesting" comments. Somehow it's devolved into discussing in general "when should you change your oil/filter" instead of observations/opinions/etc. on GM oil life monitor operation (what I'm interested in/curious about). Everyone has their own opinion/idea on best oil-change interval mileage and type of oil/filter to use, I've got mine, you've got yours. Like others I use an OLM as a general guideline/reminder, not a "thou must not let your OLM drop below XX% before changing your oil".

Anyway - so any thoughts/ideas on what my OLM % remaining will be after my ~2300 mile R/T (over a 4 day period), given that it's currently at ~64%?

newdude · July 1, 2024

2 hours ago, Probity said:

Lots of "interesting" comments. Somehow it's devolved into discussing in general "when should you change your oil/filter" instead of observations/opinions/etc. on GM oil life monitor operation (what I'm interested in/curious about). Everyone has their own opinion/idea on best oil-change interval mileage and type of oil/filter to use, I've got mine, you've got yours. Like others I use an OLM as a general guideline/reminder, not a "thou must not let your OLM drop below XX% before changing your oil".

Anyway - so any thoughts/ideas on what my OLM % remaining will be after my ~2300 mile R/T (over a 4 day period), given that it's currently at ~64%?

Again, lots of factors here. Long highway trip being its steady or mostly steady RPMs won't lower the percentage as much as if you were doing 2300mi of straight city driving with constant stop and go.

There are plenty of observations and opinions on the first page about the OLM. Sure, some things are a bit more personal thoughts and whatnot, but generally those that really dive deep into oil drain intervals and oil analysis will throw the OLM right out the window.

Why? 2 things. Lots of variables with how you drive being one, but the bigger one? The OLM does NOT know the state or condition of the oil and its additive package. It has zero way of actually testing the "life" of the oil in there.

That's why I mentioned in my first reply that those who want to "follow" the OLM should really be getting some oil samples to see how it lines up with the OLM.

Edited July 1, 2024 by newdude

garagerog · July 1, 2024

Here's a thought, use the rest of this week planning on how to have a successful trip and using that check list to make sure you're not forgetting something important instead of wasting time on pondering on something relatively unimportant that you will have the answer to once you hit the road and your OLM drops 1% and you can extrapolate from there. Don't be the Dad of that "Home Alone" kid.

Probity · July 4, 2024

On 7/1/2024 at 11:34 AM, garagerog said:

Here's a thought, use the rest of this week planning on how to have a successful trip and using that check list to make sure you're not forgetting something important instead of wasting time on pondering on something relatively unimportant that you will have the answer to once you hit the road and your OLM drops 1% and you can extrapolate from there. Don't be the Dad of that "Home Alone" kid.

Ouch. Tough crowd on this GM forum, if I knew how easy it was to offend some people’s sensibilities asking what I did then I would have asked something really ridiculous just to egg them on.

Anyway – regards OLM question it’s all academic now. My schedule changed (even being retired my days are planned out), already had the oil/filter change supplies on-hand, so decided to do 1^st oil change early (only 1234 miles on it) before our ~2200 mile trip in very hot weather.

Because I can, I’m going off-topic now regards my oil/filter change observations – you long term GM guys/gals can roll your eyes now and stop reading, but it’s been over ~44 years since I last owned a GM PU, so here goes:

1. No obvious oil leaks from underside view of engine/tranny area. I’m old (70’s) and tall and large, never a good combo for crawling around under any vehicle even on ramps, and would gladly pay a competent dealer to do this for me, but periodically doing your own changes are most valuable just to get a feel for general overall underbody conditions and possible problems. It’s a way to be proactive with only a moderate amount of effort (although 110 deg. heat index weather here did make it a very sweaty job for me).

2. My 2wd WT CCSB “came” with a skid plate (an option I didn’t need but it’s there). Kind of underwhelmed on how flimsy it looks. But even with the plate in place, access to pan drain plug and filter is good (no felt “bra” to remove like my previous FoMoCo PU). So + points for GM on that.

3. I was surprised to find my oil pan is metal (stamped aluminum?) not composite. Guess a design change between ’23 and ’24? The 15mm head drain bolt having a rubber gasket vs. crush washer a bit of a surprise too but probably a good thing (I thought no replacement parts needed for a composite pan easy-turn drain plug so didn’t prepare ahead of time for any ‘surprises’). I’ll have to remember to get a few rubber gaskets ahead of any future oil changes.

4. Drain bolt took very little effort to loosen, oil filter wasn’t super-tight as I’ve seen others comment on.

5. Drained the oil then loosened/remove the filter. Was surprised at the amount of oil draining from the filter housing (between ½ and 1 qt? IDK…). Had the time so decided to give it a good long drain period (~1.5 hrs.).

6. On my previous ride, wasn’t possible to pre-fill the spin-on oil filter (2.7 EgoBoost with cartridge filter on top of engine), so I wasn’t in the habit of doing that. But found a TechLink bulletin DTC P06DD Set after Engine Oil Change – TechLink (gm-techlink.com) about avoiding this trouble code so figured I better do the pre-fill. Took about 7 oz. of oil to fill the PF66 before installing it. No DTC after initial start-up.

7. Ran a magnet over the bottom of my plastic waste oil catch pan, no metal picked up so that was good.

8. Used the empty fresh oil bottles to keep the waste oil for disposal. I expected to see slightly less than 6 qts of waste oil, but I actually had a couple more ounces than 6 qts of waste oil. Not sure I like that but who knows how much the initial factory fill amount was (don’t they pump it from a 55 gal. drum?). Anyway, waste oil didn’t smell like gas, I’m not fretting yet.

9. All that sticky tar-like/waxy stuff on frame and suspension members – what the **** is that all about? Surely there’s got to be a better corrosion protection method than that.

Have a Happy 4^th and Happy Trails.

garagerog · July 4, 2024

17 hours ago, Probity said:

Have a Happy 4^th and Happy Trails.

Anyone that can quote Roy Rogers is alright by me, and a Happy 4th back at ya.

Grumpy Bear · July 4, 2024

On 7/1/2024 at 9:28 AM, Probity said:

Lots of "interesting" comments. Somehow it's devolved into discussing in general "when should you change your oil/filter" instead of observations/opinions/etc. on GM oil life monitor operation (what I'm interested in/curious about). Everyone has their own opinion/idea on best oil-change interval mileage and type of oil/filter to use, I've got mine, you've got yours. Like others I use an OLM as a general guideline/reminder, not a "thou must not let your OLM drop below XX% before changing your oil".

Anyway - so any thoughts/ideas on what my OLM % remaining will be after my ~2300 mile R/T (over a 4 day period), given that it's currently at ~64%?

I put Valvomax valves on all my pans and sourced a 2.5 gallon DEF container (garbage picked from a Love's truck stop). Fits perfectly under the truck and holds it all. Our local NAPA has a tote for waste oil. The filter is a pain though. Yea, lots of oil from above the filter.

ExYukon · July 6, 2024

About that one-year countdown to zero on the OLM. I just bought an Equinox that has a manufacter date from last Fall. Based on the build date, It should be well under 50% left, but it's at 94%. So I guess they don't count down by date until it is sold.

I'll be sure to change it before its birthday regardless of what the OLM says.

Phantom 4D · July 9, 2024

On 7/1/2024 at 10:04 AM, KARNUT said:

I shortened my oil change intervals because I drive less on the interstate and keep them longer. What’s perplexing is I just retired a lawnmower after 10 years. If my brother doesn’t pick it up before the winter I may fix this one. Like the last 3 I only changed the oil once in 10 years. The oil on the stick with the last one still looks clean. The first one at my brothers house still runs. The owners manual with the new one says change the oil after 5 hours. LOL. Not in this heat. Maybe when it cools off. Like usual I’m stating experience. Not a suggestion.

I'm seeing more failures on the new engines in mowers. Breaks and Scrappem with the plastic cam shaft is the worst. Just finished a Toro Kindasuckie on a commercial zero turn with a dropped valve. 15 hours on the clock. Friend of mine has a 1960 Wheel Horse Suburban. Original owner was his father. It runs better than new machines. 4 hp, single Kohler. Only thing done was oil change, air filter, and spark plug.

Grumpy Bear · July 10, 2024

19 hours ago, Phantom 4D said:

I'm seeing more failures on the new engines in mowers. Breaks and Scrappem with the plastic cam shaft is the worst. Just finished a Toro Kindasuckie on a commercial zero turn with a dropped valve. 15 hours on the clock. Friend of mine has a 1960 Wheel Horse Suburban. Original owner was his father. It runs better than new machines. 4 hp, single Kohler. Only thing done was oil change, air filter, and spark plug.

I have a 1948 Toro 19" Whirlwind tunnel deck that runs very nice. Dad bought it for his sister when she married, and it has been passed to me. Farm service. She used it hard, long and often. Boy does it give a nice haircut. Uncle Bob was an oil geek. I'm sure it received the same services his money makers did.

redwngr · July 13, 2024

Didn't read all the responses in detail, so this might have already been covered.

The algorithm for the OPM now includes calendar time as well as 'how the engine is being used.

If it is not used at all, it will still count down so that it recommends an oil change at the same interval as recommended in the manual --- 1 year.

So if 6 months in the truck only has 600 miles on it, the OLM will say 50% since the year is 1/2 over.

Probity · July 17, 2024

Well my long-ish roadtrip is finished, it was a good one. So for some fairly useless information regards my original OLM query:

1. Trip was 2166 miles door-to-door over ~5 days, 34.4 engine hrs, so ave. 63 mph (lots of pee stops, minor traffic delays in Memphis, St. Louis, Kansas City), on the interstate hwys between 70-80 mph.

2. OLM was 99% at start of trip, 71% at end, so 28%/2166 mi. = ~1.3% oil life 'expended' per 100 miles of (mainly) highway travel over a 5 day period.

3. Pre-trip numbers (before 1st oil change) was ~5 months ownership, 1234 miles/43.5 engine hours (~28.4 mph ave.), OLM at 64% before change. So for my 'city' driving, 36%/1234 mi. = ~2.9% oil life 'expended' per 100 miles of (mainly) city driving over a ~5 month period. Time interval certainly a factor here.

So now I'm a little smarter but not really wiser. Made it home safely with the frozen and processed 1/2 cow (split with inlaws, I'm the designated beef mover each year as their SUV can't accommodate the ice chests), life is good.