M21 and diff fluid change
Thread Starter
Instructor
Joined: Sep 2012
Posts: 135
Likes: 4
From: NY
M21 and diff fluid change
I'm replacing all the fluids in the '74 C3 that I just purchased and I want to confirm that I'm using the correct/preferred fluids in the trans and diff. Forgive me, this is my first Corvette.
Is dino 80w-90 GL-5 (say Pennzoil GearPlus) and good choice for the M21 trans?
Can I use the same 80w-90 GL-5 in the diff? Do I need to add the 4oz. of additive to the diff if it's not a posi? I have the original invoice and the window sticker for the car and I don't see the posi rear listed. The posi was listed on the original order form, but it looks like it was later crossed out.
FYI, it's a one-owner L-82 car with 36k on the clock and the prior owner could not remember when was the last time that he changed the trans and diff fluild, so I'm guessing they've not been changed in years.
Is dino 80w-90 GL-5 (say Pennzoil GearPlus) and good choice for the M21 trans?
Can I use the same 80w-90 GL-5 in the diff? Do I need to add the 4oz. of additive to the diff if it's not a posi? I have the original invoice and the window sticker for the car and I don't see the posi rear listed. The posi was listed on the original order form, but it looks like it was later crossed out.
FYI, it's a one-owner L-82 car with 36k on the clock and the prior owner could not remember when was the last time that he changed the trans and diff fluild, so I'm guessing they've not been changed in years.
