Ok, so I'm changing fluids. Oil with high mile Pennzoil 5w30. Tranny with Valvoline atf4. Coolant with tech something from Walmart. And gear oil with 85w140.

The gear oil has never been changed. I read to use 75w140 for front and rear if towing a lot. That's pretty much all this truck does.

75w140 I can only find on full synthetic for $12-17 each (needing 5 for front and rear), and 85w140 is half price. Is it ok to use? A little thicker is all, which I don't think will hurt.

99 1500 5.2.

 

Don't forget the T-case, ATF +4 there as well.

 

Yes. But the 85w140 ok, no limited slip.

 

since you have the pan off install a drain plug its only like 3bucks but will save u alot of time down the road

 

I think they recommend the 75-140 for towing mainly because it is synthetic- but I'm not sure how the viscosity affects it also. I personally am not a fan of synthetic in the diff's.

 

if your towing i would run synthetic for sure. if you deside otherwise the 85w140 will be just fine it will be a little thicker when cold but will be the same viscosity at operating temp

 

Awesome. I don't care about synthetic unless it'll ruin it. Drain plug was installed in tranny 3k ago by guy that rebuilt it. Beat thing ever!

 

Also, its not bad to drink beer while doing fluid change, even if I'm doing it in the am right?

 

No not bad, might as well change your fluids too.

 

Can you run royal purples synthetic transmission fluid in the tc and tranny?