GM Oil Timing of Oil Change system...food for thought

[Rugged Brown]

Originally Posted by grayfox

Who wrote the song ? Don't look it up.

Old Coot?

[OldCoot]

Originally Posted by grayfox

Who wrote the song ? Don't look it up.

The Canadian Paul Anka

[grayfox]

Originally Posted by OldCoot

The Canadian Paul Anka

You win the popcorn...

[Big Bad Allis]

I didn't read through every post on this thread. Oil topics get hot and crazy. The only real way to tel is to perform an oil analysis and use a good method to do it. I am a lubricant engineer and work with many automotive companies, including GM, Mercedes Benz, Porsche, Nissan, Kia and Ford to anme a few. You need to establish a baseline to really determine when to change your oil.

I recommend choosing the oil you think is the one you want to use. Mobil 1, SynPwr etc. At 3,000 miles on the drain pull out a sample and have it tested. It will come back fine and recommended to continue use. It will be flagged if there's anything abnormal. Next run out to 5,000 miles on the same oil. Compare it to the 3,000 sample. It will more than likely still be good for further use. Run again at 8,000 miles and repeat. You will be able to see when the oil is ready to be changed. The scary part is that some oils just hit a way and go from being reasonably good spec'd and drop off fast.

In the analysis you will see contaminants, such as soot, silicates (dirt), wear metals if any, water, fuel dilution. The company that provides the service can help you read it. Once you have fugured this out you will not have to do this every oil change. I recommend doing an oil analysis every couple of oil changes (only when you drain) not several times throughout the change. You will be looking for any abnormalities that can lead to a reduced engine life.

Diesel guys. If your doing this and don't have a fuel dilution problem the best indicator is to change the oil when the TBN and TAN numbers are close to the same number. TBN starts out typically from the 9.5 - 13 range and TAN an 0 (zero)

Here's a very trustworthy company the we use. You can mail in your sample from anywhere in the country.

Petroleum Technologies
Petroleum Technologies Group L.L.C.

Jason

[TURBS]

Originally Posted by Big Bad Allis

I didn't read through every post on this thread. Oil topics get hot and crazy. The only real way to tel is to perform an oil analysis and use a good method to do it. I am a lubricant engineer and work with many automotive companies, including GM, Mercedes Benz, Porsche, Nissan, Kia and Ford to anme a few. You need to establish a baseline to really determine when to change your oil.

I recommend choosing the oil you think is the one you want to use. Mobil 1, SynPwr etc. At 3,000 miles on the drain pull out a sample and have it tested. It will come back fine and recommended to continue use. It will be flagged if there's anything abnormal. Next run out to 5,000 miles on the same oil. Compare it to the 3,000 sample. It will more than likely still be good for further use. Run again at 8,000 miles and repeat. You will be able to see when the oil is ready to be changed. The scary part is that some oils just hit a way and go from being reasonably good spec'd and drop off fast.

In the analysis you will see contaminants, such as soot, silicates (dirt), wear metals if any, water, fuel dilution. The company that provides the service can help you read it. Once you have fugured this out you will not have to do this every oil change. I recommend doing an oil analysis every couple of oil changes (only when you drain) not several times throughout the change. You will be looking for any abnormalities that can lead to a reduced engine life.

Diesel guys. If your doing this and don't have a fuel dilution problem the best indicator is to change the oil when the TBN and TAN numbers are close to the same number. TBN starts out typically from the 9.5 - 13 range and TAN an 0 (zero)

Here's a very trustworthy company the we use. You can mail in your sample from anywhere in the country.

Petroleum Technologies
Petroleum Technologies Group L.L.C.

Jason

As I stated previously I am going to start some oil sampling with my next oil change.
I get the sample kits from my oil distributor as we sample our fleet several times a year.

Turbs

[Timtation]

BBA, check my post #36, not a lube engin but spent time in college, ~1968 working in the gas turbine lube research group with RDS. The test I mention was done as a regular spot test and was a great predictor of test evaluation of both bearings and oil analysis.
We did a recip engine test with syn oil and got bored tearing down, evaluating, re-assembling and going through the cycle with no deterioration of either engine or oil. Due to the cost at that point we made a syn/dyno blend with much the same result. Oil tech has gotten so much better I have no reason to consider syn in any engine not in continuous service.
jmo

[Big Bad Allis]

Originally Posted by f1100turbo

As I stated previously I am going to start some oil sampling with my next oil change.
I get the sample kits from my oil distributor as we sample our fleet several times a year.

Turbs

Excellent idea. Maybe you can get them to throw you in a freebie for your personal vehicle since you run your fleet through them as well as purchase your oil from them.

Jason

[JFM-jr]

Not to derail this thread but guys who have the 2007.5 and up Duramax's what kind of fuel milage are you guys getting? I'm contemplating a switch to the dark side but have been reading the newer models suffer a pretty good hit in fuel economy over prior years.

[RKR]

Originally Posted by JFM-jr

Not to derail this thread but guys who have the 2007.5 and up Duramax's what kind of fuel milage are you guys getting? I'm contemplating a switch to the dark side but have been reading the newer models suffer a pretty good hit in fuel economy over prior years.

I have an '11. No mods , 4x4, stock tires, 3/4 ton. I get 17.5 to 18 empty at about 80. I pull around a 10k 5ver and get 10 to 11 between 65 and 70 with just a few hills to pull. No mountains. I got plenty of power to spare too.
I really like the Allison trans and engine brake. You can't get either in a gasser.

[TURBS]

Originally Posted by JFM-jr

Not to derail this thread but guys who have the 2007.5 and up Duramax's what kind of fuel milage are you guys getting? I'm contemplating a switch to the dark side but have been reading the newer models suffer a pretty good hit in fuel economy over prior years.

Totally stock 08 duramax.
17-19 hiway unloaded in the summer
15-17 hiway unloaded in the winter.

9-11 towing 14, 000# 5er.

Turbs

[JFM-jr]

F1100 do you know if the Allison is standard in the 08 model? Was there another transmission offered with the Duramax in 08?

[camper1999]

I average 12 mpg towing 12000 and about 24 mpg highway unloaded

[jevanb]

Originally Posted by JFM-jr

F1100 do you know if the Allison is standard in the 08 model? Was there another transmission offered with the Duramax in 08?

the allison is standard in all duramax models, it could of been had with a ZF6 in model years 01-05

[TURBS]

Originally Posted by JFM-jr

F1100 do you know if the Allison is standard in the 08 model? Was there another transmission offered with the Duramax in 08?

As said yes Allison is the std transmission attached to the durmax via bolts.

[JFM-jr]

F1100 I sent you a pm

[TURBS]

Originally Posted by JFM-jr

F1100 I sent you a pm

Responded.