What gear oil for 12 bolt?

[wesTXwitesnake05]

What is the best gear oil for a street driven strange 12 bolt. it has posi so i know i need 2 bottles of gm posi additive. But what do you guys think is the best brand/weight for them and how much will i need?

[99RedRagtop]

i would use like an 85-140 high grade(synthetic) type lube. like Amsoil or Royal Purple. if you are track only, then you can get by with a lesser viscosity. although i would purchase same brand additive as the lube, the stuff you have will probably be fine.

[wesTXwitesnake05]

i would use like an 85-140 high grade(synthetic) type lube. like Amsoil or Royal Purple. if you are track only, then you can get by with a lesser viscosity. although i would purchase same brand additive as the lube, the stuff you have will probably be fine.

I read in another thread somewhere that it wasnt a good idea to use synthetics with a posi unit? Maybe an 85w-145 nonsynthetic with the posi additive?

[99RedRagtop]

yes, non or semi-synthetic will be fine, also.

[INMY01TA]

Neither Strange, Moser, or Eaton recomend syn gear oil for their Eaton posi's. Just use a dino gear oil. It will hold just under 2 quarts.

[wesTXwitesnake05]

the chevy house reccomended 85w 90 for 12 bolts, strange said the same. so i guess thats what i should run. i just wanted to see what everyone else was using and which was best. thanks for the info guys oh yeah... and will a heavier weighted oil help deaden some of the gear whine?

[0rion]

don't forget the friction modifier

[Hi-Po]

syn. is a no go for the rear.

[wesTXwitesnake05]

don't forget the friction modifier

what is friction modifier?