rear diff oil?

[custm86]

I've done a lot of searching and haven't found my answer. I'm changing the rear diff oil and want to be sure the WIKI is still relevant. It says to use 90/75. But some other posts ive seen recommend 70/140 with some additive. Can i get a few recommendations from the geniuses on here??? I appreciate any help!!! Thanks guys!!!! M1009 1986

 

[pmramsey]

I use 75-90 synthetic

 

[Kasper31]

pmramsey has it correct,,,,Use 75/90 synthetic year round ,,,,,,,,,unless in extrem hi temp area or are doing heavy towing then change to 90/140 type synthetic

 

[custm86]

Thanks for the help guys. ended up using Royal Purple synthetic. Its working great now.

 

[Doc Bingo]

Just curious would Phoenix Az be considered extreme high temp ... ?

 

[Iceman3005]

I have always used 80/90 non-synthetic

 

[glcaines]

Just curious would Phoenix Az be considered extreme high temp ... ?

In the summer yes, IMHO.

 

[DieselBob]

Just curious would Phoenix Az be considered extreme high temp ... ?

At 110 in the shade I would say yes

 

[Blue2actual]

I've always used 80/90 non syn