Questionable OCI indicator on GM trucks

[paulswagelock]

My 2010 Tahoe has the oil life indicator. Based on my driving conditions, it regularly call for a 15,000 mile OCI. I am all for extended intervals, but 15,000 miles on conventional oil? So far I have completely disregarded it and changed every 6000-7000 instead (Mobil 1).

Does anyone think this thing should be followed? I am sure there is a complicated algorithm running in there, but 15,000?

 

[spasm3]

I see in your signature that you do 50,000 miles a year, if you do all highway then 15,000 could be reasonable. I might use mobil ep. If you do a mix of highway and stop an do i'd do 7-10,000 on the mobil 1.

 

[5sfe91]

You must do a lot of highway/constant, non-stop and go driving. If you're using M1 i'd follow the OLM without question

 

[tig1]

My brother in law has a 2002 Silverado, and he changes every 10K with M1. No problems at all. Like you, I wouldn't go 15K with dino either. However it would be interesting to see how the engine held up doing 15K OCI after 200K. I do weld repair for several auto machine shops and repair shops in the area. Just yesterday I looked at two alum cyl heads from a 05 Ford F150 for weld repair. Beside that engine was another Ford 4.6 with only 55K, and it was so filled with sludge the engine had to be replaced. No idea of the maint. history.

 

[Falcon_LS]

Not sure if there has been a recalibration for the new Dexos spec, but a friend of mine has a '07 Tahoe Z71 and the OLM suggests a change every 15-17,500 km (9,375-10,940 miles). He uses Motorcraft Synthetic Blend 10w30, puts about 37,500 miles on it a year and does about 70% highway driving. If all your trips are highway, I don't see why not.

 

[901Memphis]

Originally Posted By: paulswagelock
My 2010 Tahoe has the oil life indicator. Based on my driving conditions, it regularly call for a 15,000 mile OCI. I am all for extended intervals, but 15,000 miles on conventional oil? So far I have completely disregarded it and changed every 6000-7000 instead (Mobil 1).

Does anyone think this thing should be followed? I am sure there is a complicated algorithm running in there, but 15,000?



If your sig is correct and you do that many hwy miles i would be more willing to follow the OLM on the mobil 1 and call it a day.

I can understand how you would not want to go 15k on conventional, but with all hwy miles its possible.

 

[opus1]

Hate to sound like a broken record here, but if it's all highway driving, the OLM is most likely accurate.

Granted it's not the same engine, but my Cobalt's OLM right now is projecting a 13,000 mile OCI since I primarily use it on the highway. If I start doing more around-town driving, especially at this time of year, it'll drop, but still take me to 9000 miles or so.

 

[Spazdog]

holy schnike!

You'd have to realize how many GM vehicles I see every day that the oil life monitor reads 0%. How far have they gone on that oil?

 

[JustinH]

Originally Posted By: opus1
Hate to sound like a broken record here, but if it's all highway driving, the OLM is most likely accurate.

Granted it's not the same engine, but my Cobalt's OLM right now is projecting a 13,000 mile OCI since I primarily use it on the highway. If I start doing more around-town driving, especially at this time of year, it'll drop, but still take me to 9000 miles or so.


I'm all for extending drains, but I'd love to see a used oil analysis on a 13k "Highway only" run with GM supplied motor oil and filters.

Sure you can get to the end of your warranty period, but I seriously have to question that amount of miles.

My brother has a newer Impala, and is currently running 6-7k miles on generic bulk dino from a lube shop.

Is it that cars are now appliances and require this little maintenance? I don't think that many low tier conventional oils are up to the task. The synthetics would be no problem.

 

[buickman50401]

Originally Posted By: JustinH
Originally Posted By: opus1
Hate to sound like a broken record here, but if it's all highway driving, the OLM is most likely accurate.

Granted it's not the same engine, but my Cobalt's OLM right now is projecting a 13,000 mile OCI since I primarily use it on the highway. If I start doing more around-town driving, especially at this time of year, it'll drop, but still take me to 9000 miles or so.


I'm all for extending drains, but I'd love to see a used oil analysis on a 13k "Highway only" run with GM supplied motor oil and filters.

Sure you can get to the end of your warranty period, but I seriously have to question that amount of miles.

My brother has a newer Impala, and is currently running 6-7k miles on generic bulk dino from a lube shop.

Is it that cars are now appliances and require this little maintenance? I don't think that many low tier conventional oils are up to the task. The synthetics would be no problem.


It'd probably be just fine to go 15k on a syn, but a dino might be pushing it.

When I was commuting during my last 2 years of college, my Buick's OLM would trip every 12-14k mi. This was about 85% highway driving. I just used Pennzoil Platinum or Quaker State Synthetic and changed it every 10k which was about 2x a semester.

 

[4ever4d]

I also have questioned the olm on our Trailblazer as it will carry an oc 8500-9500 miles on Pennzoil conventional i feel that is a bit too long,but no harm up to this point so i'm gaining confidence with this whole olm system thing,slowly.I normally change at 5-10% oil life and this shortens the oci by a few miles that helps my feelings somewhat.

 

[Jim Allen]

Thing to remember is that the OLM was calibrated for whatever was factory fill for that truck. The system itself cannot tell what kind of oil you install later after draining the factory fill. If you install oil better than the calibration oil then you have some built in leeway. If you install lesser oil, you go in the opposite direction. If the OP will so some searches on BITOG, he will find some very interesting discussion on the GM OLM from some years back, including some info from a person who helped design it.

 

[rclint]

What is the oil capacity on the engine in your 2010 Tahoe ? That would make a difference if you have a large sump, and combine that with highway miles.

I'm on the fence on the sure if it was synthetic bag, I think today's conventional oils are closing the gap on synthetic, and fast at that,... The way I look at it (rule out Mobil 1 Extended Performance, Castrol Edge, extended drain oils) and you really don't get much more mileage out of an OCI between conventional, and synthetic. Pennzoil conventional I would go 8k on easy in my Accord, and really see no problem with going 10k, and I may go to 13 k or so using PP...

 

[NateDN10]

Originally Posted By: rclint
What is the oil capacity on the engine in your 2010 Tahoe ? That would make a difference if you have a large sump, and combine that with highway miles.


^^This^^

If it's got an 8 to 10 qt. sump, 15,000 mile OCIs, all highway, should be attainable.

 

[steve20]

wife's 04 Tahoe uses 1% every 1000, straight highway driving FL-NJ. sustained 75-85mph with a 4.11 rear so we're turning 3K all day/night long.
I did a used oil analysis with using 128% of oil life (about 8K miles)last Spring. Amazed at the good results
capacity 6 qts.
With that said, I'd change it ever y 10K


Steve

 

[paulswagelock]

Sump is 6 quarts.
I do not know what the factory fill was, but it does not call for synthetic in the manual, just to follow the GM spec.

That said, I think you all have convinced me that 6k is a little early given I use synthetic, and 10k seems to be the consensus on the max.

 

[JOD]

Originally Posted By: paulswagelock

Does anyone think this thing should be followed? I am sure there is a complicated algorithm running in there, but 15,000?


Yes. The OLM has been discussed in detail, in one particular thread, with a GM engineer giving his input. You can find it if you search,but the bottom line is that after reading that, I trust it.

I also wonder just how much difference there is in base stock composition between a conventional GF-5/Dexos/SN rated oil, and a US-defined synthetic? My guess is, "not much".

You should also take a look at some long used oil analysis on conventional if you want some proof:

https://bobistheoilguy.com/forums/threads/11-577-miles-gf-5-pyb-2008-chevrolet-impala-v-6.140368/

https://bobistheoilguy.com/forums/threads/pp-5w-20-14-658-on-oil-5-7l-hemi.139675/

If you're really nervous about it, why not run the OLM to 80% and have the oil analyzed? I imagine it would give you real piece of mind. I think the OLM is a lot better indicator of the oil's condition than time, mileage, or internet speculation!

 

[The Critic]

Originally Posted By: Jim Allen
If you install oil better than the calibration oil then you have some built in leeway. If you install lesser oil, you go in the opposite direction.


Depending on the specific circumstances, all oils will be the same. All oils will pick up contaminants (blow-by and fuel dilution) at the same rate. Also, all oils likely contain about the same amount of anti-wear additive as well, due to the API and ILSAC regulations. Therefore, the only real differences between most synthetic oils and conventional oils are the slight improvement in oxidation resistance with synthetic and the added detergency in certain brands, which may or may not be useful. Therefore, based on those assumptions, oil life is going to be the same.

 

[GMBoy]

Originally Posted By: Spazdog
holy schnike!

You'd have to realize how many GM vehicles I see every day that the oil life monitor reads 0%. How far have they gone on that oil?



Probably (atleast I hope so!) these people never reset the OLM display. If not...than I'm with you - how far have they gone??!

 

[Ken2]

Paul

An oil analysis or two will tell you exactly what's happening and at reasonable cost compared to dumping synthetic oil that is still good. I think the OLM is correct, but run 10k and send in a sample.

The better synthetic oils can contain higher quality (higher cost) additives which give a longer oil life. A look at the used oil analyses usually shows that oil life is ended due to oxidation and/or additive depletion, not contamination.