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2008 Gmc What Oil

Hahaha. Rotella is now CJ-4 rated, so you should be fine using it. Make sure the API service rating is CJ-4. It's a low-ash version of the normal stuff. They've been busy changing everything over to the treehugger versions, so it's hard to walk into Autozone and NOT walk out with CJ4 now. Oh well. You could also dump the pesky little DPF and run whatever you want. Good luck :).
 
Amsoil makes a great 5-40 synthetic that has some really good test results thus far. I run the 5-30 HDD Amsoil syn, but you cant run that in a DPF truck without hurting the DPF.

I have Amsoil from front bumper to back, and I love the stuff. I know some on the site are likely to be haters, but I am soon to install the dual remote by-pass filter so I wont change the oil again, only the filters and top off! Ofcourse I will sample every 20K, but you get the point.

Tony
 
Horsehaulin said:
Amsoil makes a great 5-40 synthetic that has some really good test results thus far. I run the 5-30 HDD Amsoil syn, but you cant run that in a DPF truck without hurting the DPF.

I have Amsoil from front bumper to back, and I love the stuff. I know some on the site are likely to be haters, but I am soon to install the dual remote by-pass filter so I wont change the oil again, only the filters and top off! Ofcourse I will sample every 20K, but you get the point.

Tony
Click to expand...

I understand that filtration is a key component to oil life and extending it,but does not even synthetic oil shear and loose acid fighting abilities(additive depletion)??? How can extra filtration make the oil "forever"??? I'm an Amsoil user,so I'm not bashing just asking.
 
Bammer said:
I understand that filtration is a key component to oil life and extending it,but does not even synthetic oil shear and loose acid fighting abilities(additive depletion)??? How can extra filtration make the oil "forever"??? I'm an Amsoil user,so I'm not bashing just asking.
Click to expand...


"Forever" is not a term I would use. "A really long time" is more like it. The bypass filtration systems are 98.7% efficient down to 2 microns (that's REALLY good). Because of this the contamination levels remain very low, this allows the additive package (detergents, etc) to last much longer. Also, as filters are changed (full flow at 25k miles, Bypass filter at 50-60k miles) new oil must be added to refill the oil system. This introduces more new oil and additives to the system.

Shearing with a full PAO synthetic is not nearly as much of a concern as it is with Group III and II oils because the Group IV PAOs have a uniform molecular size and therefore don't need the long chain hydrocarbon viscosity improvers. That means minimal shear.

Acid fighting capabilities are not challenged as much with the bypass system because of the superior soot and contaminant removal, and detergents do not get expended as quickly because they don't need to buffer as many contaminants.

The most reaponsible and honest answer I can give is this: With a bypass system you can significantly extend drain intervals using oil analysis, 80k miles is common. Forever, while possible, is not.

Hope this answers some of your questions.
 
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