Engine oil selection for 2002 Tahoe 5.3

mjoekingz28 · September 21, 2016

I run 10w-30 in the 6.0 which is similar to yours. I run it year round from 20 degrees to 100 degrees Fehrenheit. My oil cap states 5w-30 but I think that is just to make it easy for the whole country. The owners manual says 10w is okay for above 0 degrees.

What I am concerned about is oil or engines have changed over the years. Twenty or thirty years ago or so, oil grade selection was temperture dependent. Say for summer you would select 20w-50 and a cold winter you'd use 5w-30. Now, 5w-20 seems to work year round. I do not know what changed. Was it better oils and additives or better metallurgy and oil cooling in the engine, I do not know.

Also, there are reports that around the world use different viscosities than we use for identical engines here in the States. I would use a 10w-30. That is what I use but I still havent decided on conventional, synblend or full synthetics.

Good luck!

Dmitriy · September 21, 2016

I run 10w-30 in the 6.0 which is similar to yours. I run it year round from 20 degrees to 100 degrees Fehrenheit. My oil cap states 5w-30 but I think that is just to make it easy for the whole country. The owners manual says 10w is okay for above 0 degrees.

What I am concerned about is oil or engines have changed over the years. Twenty or thirty years ago or so, oil grade selection was temperture dependent. Say for summer you would select 20w-50 and a cold winter you'd use 5w-30. Now, 5w-20 seems to work year round. I do not know what changed. Was it better oils and additives or better metallurgy and oil cooling in the engine, I do not know.

Also, there are reports that around the world use different viscosities than we use for identical engines here in the States. I would use a 10w-30. That is what I use but I still havent decided on conventional, synblend or full synthetics.

Good luck!

Thank you for the reply!

Dmitriy · September 21, 2016

All oil has considerable additives in them. Usually up to 20% (and sometimes more) of any motor oil is additives. Base oil is clear like water. The color you see when you pour fresh motor oil is additives. Additives control friction, provide extreme pressure modification, control acids, emulsify ethanol, provide detergents for engine cleaning, provide suspension for particulates, control oxidation, and the list goes on. Run a base oil with no additives, even a top end full synthetic base oil, and you will grenade a engine in a short time.

But what is indeed higher is viscosity modifiers. A 0w40 uses quite a bit of them. It is VM that can shear under pressure and break down. And the NOACK, or burn off vaporization rate, is higher in oils that need more VM. The base oil itself doesn't. I never felt the need for a 0wXX oil, even when I was living in the interior of Alaska for 10 years. When things got that kind of cold, we were sensible enough to use block heaters, oil pan heaters, battery warmers, auto trans pan warmers, and winter grill fronts on our vehicles. Only an ignorant person would have an vehicle sitting overnight at -45F and not use preventative measures like that. When one does the right thing, a engine can start at -55F like it is a warm summer day, and do it on a conventional 5w30, which is what I used all those years in Alaska. Never had one engine problem or oil related issue.

The less spread between the cold flow rating (the number before the "w") and the oil viscosity (the number after the "w), the fewer viscosity modifiers are needed. Yes, even full synthetics need some viscosity modifiers except some of the Group IV PAO oils of the 10w30 variety.

I live in central Iowa, and I have no problem using 10w30 in just about everything I own, year round. From my smaller stuff, on thru my personal vehicles, on up thru my commercial trucks. I have various reasons for doing so that I am comfortable with. And my Silverado and Cadillac sit in a heated garage when at home. For most folks, i would just tell them to stick with the OEM recommended viscosity and call it a day. Unless one is having a major problem they are trying to address, there is no real need to go to extremes in what oil they are using.

Thank you for the extensive reply!

Dmitriy · August 20, 2017

I noticed some oil traces around the oil plug coming from above. I am going to clean it up and check if the oil is leaking and if oil grade is the cause. Thanks for the advice!

Hello Everybody!

Have not been posting here for around a year)

Getting back to the oil leak - It is Rear Main Seal - I am losing 1 liter of oil per 5000km in very hot period in summer. Other than that it is ok, so I have been told that i do not have to mess around with it as it is pain to change it... But I still consider putting a new one till the end of the year.

As per oil selection- I use AcDelco 5w30 API SN/ILSAC GF-5. But we have in stores new Lukoil 5w30 dexos2 http://lukoil-masla.ru/en/Products/ProductCard?product=50. Unfortunately we do not have GM recommended dexos1 grade oils here. Lukoil factory support assured me that it is possible to use dexos2 though I have read information that dexos2 is recommended for diesel engines: http://www.centerforqa.com/dexos-brands/

Would you recommend switching to dexos2?

Thanks in advance!