Excessive Oil Change Interval permitted by OLM??

[WarGawd]

Hey folks, been a while

Search has turned up nothing related to my question so I'll post it.

Last June I moved from one town to another, and started driving way more highway mileage than I had previously.

Last fall sometime I was getting a code that I traced very quickly to my CPAS having eating its screen. I was able to pull out most of the screen bits that had gotten jammed in the actuator body and ran it a couple days with no code. Then I replaced it with a brand new part (obtained at local dealer for a surprisingly competitive price).

The above may or may not be related to the issue but seems like the only thing that has a remote chance of offering some explanation, but since that point in time I've noticed that my OLM permits what I'm starting to think are excessively long oil change intervals....that last 2 have been in the vicinity of 18,000+ km (~11,000+ miles).

Anybody care to share their example of long OCI's for comparison? Anybody else ever hear of the OLM permitting excessively long OCIs?

I'm kind of wondering if it's possible that some small part of the disintegrated CPAS screen worked it's way in and jammed in some narrow channel and is perhaps restricting oil flow to/from some area and thereby altering some data point on which the OLM / OCI is based. Or is it just the sudden jump to vastly more highway miles driven that's allowing longer intervals than I've experienced in the past?

Anybody know the exact algorithm / process for the OLM to arrive at it's indicated value?

Ok, I'll leave it there for now. Thanks all in advance.

EDIT 1: I've been running full synthetic always since I first bought the truck some 180k+km /6 yrs ago
EDIT 2 : @Sparky seems to suggest in this post that 10-12k mile OCI's are common...so for the moment I'm taking that as a good sign and assuming I was only getting 10-12k KM due to the higher demands of primarily city start/stop driving

 

[DAlastDON]

The OLM does not analyze the oil itself in any way. It is an algorithm that takes into account, idle time, rpm, speed, etc...and calculates the OLM percentage. It does not take into account the oil level, type, or anything else. Since purchase in 2014, I do annual oil changes with mobile 1 synthetic at 10k miles. OLM is usually at around 20%. I usually have about 1/2 to 3/4 quart consumption between OCI's on the I6.

 

[littleblazer]

I ran out 14k with about 10% left. It's a pretty sophisticated algorithm. I believe it was based off interpollating data from various test engines.

 

[christo829]

I run someplace around 10k miles before the OLM gets around 10%. Since I'm running synthetic, I'm not too worried about it.
I just make sure it's full. Your increased interval is probably due to the highway driving. A lot of stop and start city driving usually makes
my oil life % drop faster.

Cheers-

Chris

 

[Reprise]

What everyone else said. While a lot of people like to discount the accuracy of the GM system, it's supposed to be regarded as one of the best ones, especially for when it was introduced. Some actual engineering-type effort went into its development.

Some of the systems other makers were using at the time (cough *Ford* cough) were purely odometer-based. I remember owning a late-80s Thunderchicken that was pretty loaded - and the OLM display was comprised of 'OK' , 'Soon', and 'Now' (oh, and they were lighted in green, yellow, and red, respectively). Real cutting-edge tech, there. Better than nothing, I suppose.

'Our' version in the GMT360s is calibrated for conventional oil, so if you've been using synthetic since it was 'new to you', you need not worry about stretching too far, per the OLM percentage (e.g.; you safely have some 'more' life to go, using synthetic). If you were still under powertrain warranty, I'd tell you not to go all the way to 'zero', but that's about it. Unless you start doing oil analysis, though, I wouldn't push it - just get ready to change it at 10%, and you'll be more than fine. No need to 'sweat' it, if you're using synthetic.

The only time not to follow it is if you use the vehicle on an 'occasional' basis. In those cases, your change interval becomes time-based (1yr). I generally have about 60-ish % left when my yearly oil change comes up. That's going to change now, as I'll be driving the Voy more often now - and towing with it besides (yes, the OLM knows when you're towing - it detects load - via the PCM / ECM)

 

[WarGawd]

Thanx all

Took me a couple days to get back here but you all seem to have confirmed that I was worrying too much when I'm actually experiencing "normal" behavior.

For once, no problem to tackle here

Cheers

 

[Mounce]

I'll go against the grain and say I believe in the old 3k internal no matter what oil is used. One of the few that think this way but after a couple pure nasty oil changes relying on the olm I kicked it to the curb.

I don't mind spending the extra money doing "early" oil changes to ensure my engines are well maintained oil wise.

 

[Mektek]

look at your oil on the dipstick. If it's a chocolate brown then you're due for a change. If it looks light transparent brown and the OLM shows plenty of life then it's fine - especially if you're using synthetic. 3000 mile intervals were recommended decades ago in the days of mineral oil with low SAE ratings. Today's brand name oils are much improved and in a good running engine should be fine for at least 5000 miles.
There are some lawn mowers that advertise that the engine never needs an oil change...........

 

[vipergg]

I normally dont follow the OLM and do mine somewhere around 6000 miles. Never seen the OLM on before . with 7 quarts in the sump I figure this is soon enough to keep it fairly clean .

 

[c good]

I run synthetic blend Valvoline. Change it every 5000 miles regardless of what the sensor tells me. HTH....c good

 

[BrianF]

It seems mine has been stretching out longer and longer as well but to be honest I have not paid much attention to the Tb in some time. I usually run mine out to 24,000km before changes. I had hoped to actually do used oil analysis on mine to get some fact behind my decision but never actually pulled the trigger (just started doing UOA on my Ram with the 6.7 ISB). I just rolled over 220,000km and it does not seem to consume any oil during this index and runs about as good as it ever did (still need to do the stupid thermostat).

 

[mntegra01]

As far as GMs go, it states in their Service Information that techs use, that burning oil one quart per 2000 miles is acceptable. Yes it is owner responsibiltyI understand that a 3000 mile oil change may be excessive, but I see more vehicles in the shop from LACK of maintenance. Early Acadia 3.6 timing chain issues would probably have not been so prevalent if the oil had been changed at around 3000-4000 miles instead of OLM.

i'm only 34 and I strongly go with the 3-4K mile oil change. I'm not old school, but I have had no problems with the vehicles I have owned that I have serviced, as far as engine goes.

 

[shovenose]

Everybody has their own opinion on this. I do 7500 mile OCIs on full synthetic.

 

[littleblazer]

See I changed mine in March and I am at 7k... I change it too much as it is already.

 

[Eric04]

The change I just did on the TB was at 6000 mile interval with 30% on OLM but it looked dirty so I hit it "early". A lot depends on each person's driving habits, IMO. I drive very little city so I'm comfortable stretching well beyond the 3K marketing campaign suggestion. However, if I was predominantly city I'd likely stick to a shorter interval. Oil and filter quality also play a role. So like most everything else, many variables and personal preferences.

Now on my old Impala with the 3.8, you can darn near run it dry of fluids and it'll still run. Not that I'd ever neglect it but just saying it is a pretty tough old motor. 👍