What gear oil should I use

[87 national]

I know I do not have stock gears. Speedo says about 45 when doing 50-55. No tags on rear at all. What oils should I use in the rear. Also my car was original g80 so should I use the limited slip additive?

 

[novaderrik]

your gears might still be stock, but the trans could have been changed out at some point without swapping the proper drive and driven gears into the replacement. taller tires will also make the speedo read low like that.

i'm a fan of Amsoil gear oil- it's about the best readily available brand- get the good stuff and run it without any sort of additive.

 

[87 national]

your gears might still be stock, but the trans could have been changed out at some point without swapping the proper drive and driven gears into the replacement. taller tires will also make the speedo read low like that.

i'm a fan of Amsoil gear oil- it's about the best readily available brand- get the good stuff and run it without any sort of additive.

My gears have been changed the previous owner told me what they were and i wrote it down some where but now i cant find it. Also what weight should i run?

 

[EVIL]

If the gears were changed to a higher gear then the speedo would read 55 when doing 45 or something to that effect.

 

[TURBOPOWERED68]

I know I do not have stock gears. Speedo says about 45 when doing 50-55. No tags on rear at all. What oils should I use in the rear. Also my car was original g80 so should I use the limited slip additive?

i just had my rear rebuilt (Eaton POSI, and new gears)and the builder told me to use "cam2 80w90 extream pressure"

if i didn't ask i would have gotten limited slip deferential fluid which he said would have ruined the rear.

i would open the cover and verify whats in the rear then buy the right stuff instead of risking $1200 on a rebuild over a guess of what type of oil to use.

Good luck

 

[driveshaft man]

Only the lack of oil will"ruin" your diff. High performance gear oil has some friction modifier in it...which is slicker than regular oil and makes the clutches slip without chatter. Use any name brand 80w90 HP rated gear oil. Chatter means the clutches and doing their job, but if it bothers you , add a bottle of GM Posi additive, and if it still bothers you ,add a bottle of Ford Posi additive, but this alters the ability of the clutches to adhere to each other