versus 75-90 in a 3.23 sure grip in a B-body. I live in florida if that makes a difference? i am thinking i bought the wrong gear oil. Rats!!!

anyone? thoughts?

I used Lucas gear oil it has the Additive in it
already. No problemo...

Iam running royal purple 75-140 in my rear 8 3/4 3.55 yukon gears detroit tru trac. I don't run the additive aas the tru truc doesn't need it. Also i drive the car all year even in the cold winter and haven't had a problem been 4 years now. "i did break in the rear with dino oil the first year"

ok, now i am a little confused. What i was curious about is whether 90 weight is better suited than the 140 weight?

Buuuuut, what is the additive you've mentioned.....do i need to run an additive with royal purple synthetic....and what additive? Is this for the sure grip.

By the way, this is not a new unit, just reinstalling the unit that has been in the car for a while.

k.i.s.s. A hotter climate and even more so is hot rodding it requires a thicker fluid. I'd suggest the 85-140 but I'd see what the doc has to say for the final word

well, if i understand the ratings correctly, the 75 (or 85) is the viscosity rating when cold (very cold) and the 140 (or 90) is the rating when hot....so it would seem the 90 might be better, but i am not sure. I know chrysler recommends the 75w-140 on the new trucks and jeeps...but it has to be synthetic.

My car is a 69 bee with a 496 stroker making about 570hp and a 727 trans....3:23 sure grip rear and 20x10 rear meats about 30 inches tall. xhd expo springs, frame connectors and hotchkis front and rear bars and upper a-arms.

I running it in my duster 8 3/4 clutch surgrip 3.23 gears. Bottle said the additive is in there so I've been running it streigt. about 5k and no problems so far.