I have just bought a nice 2000 Express LS passenger van with a 5.7L engine and a 4L60E transmission to use as a work van. I have a couple of questions:

Anyone run full synthetic engine oil in their Express?
If yes which brand and why?
Engine oil seems to have been changed every 3000 miles with Dino oil.


Also I notice a slightly rougher shift when my transmission is hot. Fluid looks nice and clean and does not smell burnt.
Thinking Synthetic ATF might help? Royal Purple?
Is synthetic AFT worth the $80 cost? or should I just replace the filter and refill with Dex/Merc?

Anyone fitted an AFT cooler to this transmission? Worth the cost? I do not tow but carry 800lbs of tools daily.

Thanks for all your help!

 

All oil is petroleum base. Synthetic oil has a synehthesized hydrocarbon.

 

Is Synth ATF worth the cost in your mind? Is it any better for the Transmission?

 

The only thing I see in synthetic is it lasts alot longer. I use it in my Mazda as my daughter was driving it while in school, and I know I am the ONLY one whom changed oil when se came home.

 

Thanks kevinkpk! Yep the extended drain times are useful! And I have run full synthetic engine oil in high performance turbo charged cars which need the extra heat protection synthetic gives.

I have heard good things about Synth ATF. Just looking to see if anyone runs synthetic ATF in their Express 4L60E transmissions, which brands they use and and if they get good results.