Posi Additive

[Thundergun]

Hey Guys - I did some searching, but couldn't find exactly what i'm looking for on here.

Can anyone comment on whether or not the standard Valvoline gear oil with the limited slip additive is good enough for a posi rear end unit? I know everyone is saying get the extra additive, but this stuff already has it mixed in. Thoughts?

Also, i see a lot of ppl here saying 80/90 is the right gear oil, but my original 1985 owners manual calls out 75/90 (unless my memory is mistaken). What gives? I'm super paranoid about little stuff like that.

It's an 85 K10, SB. 3.73's. Original front diff. Just got a rear out of an 87 burban, posi (oh yeah!). I put 80/90 Valvoline Syn with Limited slip additive already mixed in.

Also, is there a difference between posi and limited slip additives? heck, what is the difference between posi and limited slip?

Thanks!!

[Captkaos]

Gear oil is typical of the environment you are in.  Most GM limited slips call for additive, what brand has it in it?
a Posi (Positraction) is what GM called their limited slips.

[Thundergun]

Thanks CaptKaos.

I purchased the Valvoline Synthetic 80/90 with the limited slip additive already in it. Should i purchase  additional additive?

Is 80/90 the right stuff or should i go with the owners manual recommend of 75/90?

[Thundergun]

I guess i should add my environment is a coastal community in CA near the beach. Its stays about 65F +/- 12 degrees average for the year.

[Captkaos]

I think you will be fine with what you have.

Chris Lucas
73-87chevytrucks.com
captkaoscustoms.com
squarebody.biz

[Thundergun]

Thanks CaptKaos!