GM OLM gone crazy?

[Slippery_Pete]

I've never really payed attention to the OLM before. It's at 75% with a little less than 3k on it. So that roughly 11k for the OCI.

Should I run it out?

I am especiallly consernd due to the fact that this is dino oil and it's getting to winter (dust and salt gets everywhere) and my car has an aftermarket K&N filter on it.

 

[crazyoildude]

during the winter months it will compensate... it works pretty good i like to stay under 7000 miles on dino also

 

[willix]

That sounds reasonable.

Since 2002 some of the GM cars have a GF-3 oil spec. with a 12,500 mile OCI interval.

Most the mantainence schedules don't specify a mileage interval at all unless the OLM is accidentally reset.

They prefer you depend on the OLM.

I get impatient with the OLM too.

 

[beast3300]

Nice car! My 98's calculation to 0% seems consistent with my driving habits. Extrapolating where it is now (I think it is at 42%) it puts me on track for 5k.

 

[chubbs1]

That is where I have a problem with OLM's. They can't tell what type of oil you put in nor the condition of it. I change my Honda out between 50-40% That is usually around 5.5K. Just use your best judgment along with the OLM and you should be fine. Look how many oils are at a critically low TBN at 8-12K, even premium oils.

 

[The Critic]

Originally Posted By: chubbs1
That is where I have a problem with OLM's. They can't tell what type of oil you put in nor the condition of it. I change my Honda out between 50-40% That is usually around 5.5K. Just use your best judgment along with the OLM and you should be fine. Look how many oils are at a critically low TBN at 8-12K, even premium oils.

All oils, will probably last about the same amount of time due to the similar levels of anti-wear additives. Regardless of oil type, you will still get contamination from blow-by and fuel dilution which will require an oil change. The premium products may have more detergent, but that doesn't mean the oil is not contaminated.

 

[J. A. Rizzo]

Originally Posted By: The Critic
Regardless of oil type, you will still get contamination from blow-by and fuel dilution which will require an oil change. The premium products may have more detergent, but that doesn't mean the oil is not contaminated.


Oil is contaminated as soon as you pour it in. The question is how much contamination can it handle. So that should be your goal. Find out how much contamination it can take, and if you want to spend less money on maintenance, run the oil out as long as it can last. 5500 or 50% on a modern engine, modern oil, modern OLM is a waste of resources by probably double what the systems can handle. Being unwilling to find the limit doesn't mean you're maintaining the vehicle properly or better than average. It means you're maintaining it inefficiently and putting more money into the pockets of oil companies. What tangible benefit do you get from over-changing oil? Is it all psychological, or can you point to definitive problems by following an OLM?

 

[The Critic]

Originally Posted By: J. A. Rizzo
Originally Posted By: The Critic
Regardless of oil type, you will still get contamination from blow-by and fuel dilution which will require an oil change. The premium products may have more detergent, but that doesn't mean the oil is not contaminated.


Oil is contaminated as soon as you pour it in. The question is how much contamination can it handle. So that should be your goal. Find out how much contamination it can take, and if you want to spend less money on maintenance, run the oil out as long as it can last. 5500 or 50% on a modern engine, modern oil, modern OLM is a waste of resources by probably double what the systems can handle. Being unwilling to find the limit doesn't mean you're maintaining the vehicle properly or better than average. It means you're maintaining it inefficiently and putting more money into the pockets of oil companies. What tangible benefit do you get from over-changing oil? Is it all psychological, or can you point to definitive problems by following an OLM?


I never said there was an issue with following an OLM. There has yet to be any proof that synthetic oils can handle more contamination than conventional oils. If there is, I would like to see it. My point is that both oil types will be contaminated from normal operation and if the OEM has designated certain limits for contamination as a guide to determining the proper service interval, then their recommendation should be followed.

 

[El_Schaf]

I have had a lot of experience with the GM OLM and the 3800 that is likely in your car. I can say that, when it comes to TBN and wear metals, my OLM comes up with a shorter drain interval that the oil could do, based on Oil analysis; This was using Castrol Edge, Mobil 1 EP, and taking the OLM out to roughly 12,500 (I do a lot of highway driving). I have read on this board, and believe, that the GM algorithms are set up to be based conservatively on the least robust API oil that is spec'd for the car. The only major difference that I have noticed between synthetic and standard oil is the amount of volume loss over the miles (burn off, volatility, what have you). Synthetics have been a cut above, requiring a quart or less of the 12,500 miles, where the dino oil I ran for three 7000 milers required roughly 3/4 to 1 quart in that time. Oh, and there was noticeable yellowing of my rocker arms when I switched to dino at roughly 85,000 miles. They looked new prior to that. I am currently at 118,000, running PP, and I cant get that yellow to go away... PU is my next OC.

 

[beast3300]

Originally Posted By: El_Schaf
I have had a lot of experience with the GM OLM and the 3800 that is likely in your car. I can say that, when it comes to TBN and wear metals, my OLM comes up with a shorter drain interval that the oil could do, based on Oil analysis; This was using Castrol Edge, Mobil 1 EP, and taking the OLM out to roughly 12,500 (I do a lot of highway driving). I have read on this board, and believe, that the GM algorithms are set up to be based conservatively on the least robust API oil that is spec'd for the car. The only major difference that I have noticed between synthetic and standard oil is the amount of volume loss over the miles (burn off, volatility, what have you). Synthetics have been a cut above, requiring a quart or less of the 12,500 miles, where the dino oil I ran for three 7000 milers required roughly 3/4 to 1 quart in that time. Oh, and there was noticeable yellowing of my rocker arms when I switched to dino at roughly 85,000 miles. They looked new prior to that. I am currently at 118,000, running PP, and I cant get that yellow to go away... PU is my next OC.


The yellowing might be part of Pennzoil's additives. All the engines I used Pennzoil in get the same color.

 

[El_Schaf]

AH, the yellowing happened on dealer bulk. I figured a 50% oci would be ok on those, since they were free. Never again...

PS -I did use PYB for my top off's

 

[JOD]

Originally Posted By: chubbs1
That is where I have a problem with OLM's. They can't tell what type of oil you put in nor the condition of it.

The OLM is set to a minimum standard, based on requirements from the manufacturer. So at a minimum, it's going to err on the side of caution. As far as telling the condition of it? Well, while you're correct it doesn't measure the condition of the oil, it does calculate it based on usage--and the calculations have shown to be pretty robust, and conservative.

Originally Posted By: chubbs1
I change my Honda out between 50-40% That is usually around 5.5K. Just use your best judgment along with the OLM and you should be fine. Look how many oils are at a critically low TBN at 8-12K, even premium oils.


It's your car and you can do what you want, but the bolded comment is silly. So what? The OLM isn't going to suggest a 12K OCI unless the conditions warrant it. That's the whole point of the OLM, to calculate and estimate condition of the oil based on usage, not miles. Neither miles nor time are really great indicators of an oil's condition.

Can you provide one single instance of oil being not suitable for use while following the OLM?

 

[Slippery_Pete]

Originally Posted By: beast3300
Nice car! My 98's calculation to 0% seems consistent with my driving habits. Extrapolating where it is now (I think it is at 42%) it puts me on track for 5k.

Thanks. You'll see me posting on RegalGS.org under "Freddotron"
Originally Posted By: J. A. Rizzo
Originally Posted By: The Critic
Regardless of oil type, you will still get contamination from blow-by and fuel dilution which will require an oil change. The premium products may have more detergent, but that doesn't mean the oil is not contaminated.


Oil is contaminated as soon as you pour it in. The question is how much contamination can it handle. So that should be your goal. Find out how much contamination it can take, and if you want to spend less money on maintenance, run the oil out as long as it can last. 5500 or 50% on a modern engine, modern oil, modern OLM is a waste of resources by probably double what the systems can handle. Being unwilling to find the limit doesn't mean you're maintaining the vehicle properly or better than average. It means you're maintaining it inefficiently and putting more money into the pockets of oil companies. What tangible benefit do you get from over-changing oil? Is it all psychological, or can you point to definitive problems by following an OLM?


Like others have said the OLM has no way to determine oil contamination. With my K&N air filter tucked into the fender I beleive it pulls in way more contamination than a OE set-up. There is no question that I will be changing it earlier than the OLM says. But even on a fully stock car I believe the OLM is pushing the limits of the oil. Perhaps synthetic can tolerate the extra contamination from longer OCI's but the OLM was designed around dino oil AFAIK.

Having said all that, is the rate at which the OLM drops linear as a function of miles? Assuming constant driving conditions through the entire OCI.

 

[JOD]

Originally Posted By: Slippery_Pete



With my K&N air filter tucked into the fender I beleive it pulls in way more contamination than a OE set-up..... But even on a fully stock car I believe the OLM is pushing the limits of the oil.


If you've modified the intake, then you very well may have a point. Your comments about the OLM on a stock car though are completely unsupported by the evidence.


Originally Posted By: Slippery_Pete
Having said all that, is the rate at which the OLM drops linear as a function of miles? Assuming constant driving conditions through the entire OCI.


Man, not to sound harsh, but you're questioning the OLM's efficacy without even knowing how it works?

The OLM doesn't drop in a linear function unless engine revolutions, load conditions and oil temperature are kept constant.

 

[Slippery_Pete]

Originally Posted By: JOD


Man, not to sound harsh, but you're questioning the OLM's efficacy without even knowing how it works?

The OLM doesn't drop in a linear function unless engine revolutions, load conditions and oil temperature are kept constant.

I most certainly do know how it works. When I reset it this time I noticed it fell from %100 to %99 in under 5 miles, suggesting a non linear rate of change.

Other than temperature, the factors that control the OLM should be constant enough to make a negligible difference.

 

[J. A. Rizzo]

Originally Posted By: El_Schaf
Oh, and there was noticeable yellowing of my rocker arms when I switched to dino at roughly 85,000 miles. They looked new prior to that. I am currently at 118,000, running PP, and I cant get that yellow to go away... PU is my next OC.


Thankfully yellow rocker arms have no effect whatsoever on how the engine runs or its longevity. Their effect is purely psychological - not a technical problem in any way. At 118,000 miles, no oil would have kept them completely clean, and trying to clean them can lead people to taking actions that potentially cause more problems than they solve, like putting solvents (MMO, Seafoam, kerosene, engine flushes, etc) into the oil sump. So feel free to ignore them and continue to follow the OLM recommendation with dino oil. You can learn to live with the yellow rockers. The problem is all in your head.

 

[El_Schaf]

LOL, I know it isn't a real problem. I'm just regretting taking the plastic off the couch. And since motor oil is a hobby, I need to justify the PU purchase somehow...

 

[3putter]

I've got 8400 on my '09 Malibu (Ecotec)with 31% showing on the OLM. I've had over 12k on my Buick with a 7.5 quart sump (Northstar V8)and still showing 15%. Don't sweat it. Much of SM / GF4 was about extended drain intervals for both environmental and expense reasons.

 

[Capa]

Somebody should start a thread asking what is the more reliable OCI reader---OLM or a UOA.

 

[Winston]

Quote:
I most certainly do know how it works. When I reset it this time I noticed it fell from %100 to %99 in under 5 miles, suggesting a non linear rate of change.


Um no, you need to learn a little more math. You cant really learn anything by watching it go from 100% to 99% in 5 miles. As noted, the OLM considers many factors in order to determine when to change the oil. However, it is true that it does not know that you have a K&N oil filter that allows much more contamination to enter the oil. Definately change it before the OLM tells you to.