4 replies to this topic

[vhbigman]

GM Tech,
I have a 2007 GMC Sierra crew cab 1500 4x4 with the locking differentials, what is the recommended interval for service? And is there an additive for the oil if you use synthetic?
thanks
V

[snakedoctor]

I don't remember what the manuals calls for and I am too lazy to look it up for you.

For my personal truck. I changed the diff fluid out @ 1500 miles to get shavings out. Then sense I tow I change it yearly.

GM uses a synthetic fluid. You can use Mobil 1 75/90 or Castrol synthetic 75/90. Or what ever your favorite synthetic gear oil might be. Gm DOES NOT require an additive for the Eaton G80 locker. The G80 is not a limited slip so requires nothing but gear oil. But I have a 2 wheel drive. I believe GM says to use their fluid in the front diff. Some one correct me if I am wrong.

Have a good one,

Don

Edited by dlstewart01, 15 March 2008 - 12:01 PM.

[vhbigman]

I don't remember what the manuals calls for and I am too lazy to look it up for you.

For my personal truck. I changed the diff fluid out @ 1500 miles to get shavings out. Then sense I tow I change it yearly.

GM uses a synthetic fluid. You can use Mobil 1 75/90 or Castrol synthetic 75/90. Or what ever your favorite synthetic gear oil might be. Gm DOES NOT require an additive for the Eaton G80 locker. The G80 is not a limited slip so requires nothing but gear oil. But I have a 2 wheel drive. I believe GM says to use their fluid in the front diff. Some one correct me if I am wrong.

Have a good one,

Don

thanks
v

[vhbigman]

What are the capacities of the front and rear differiental and what is the part number for the front diff fluid and does it require and additive.
thanks

I don't remember what the manuals calls for and I am too lazy to look it up for you.

For my personal truck. I changed the diff fluid out @ 1500 miles to get shavings out. Then sense I tow I change it yearly.

GM uses a synthetic fluid. You can use Mobil 1 75/90 or Castrol synthetic 75/90. Or what ever your favorite synthetic gear oil might be. Gm DOES NOT require an additive for the Eaton G80 locker. The G80 is not a limited slip so requires nothing but gear oil. But I have a 2 wheel drive. I believe GM says to use their fluid in the front diff. Some one correct me if I am wrong.

Have a good one,

Don

[Zembonez]

I don't remember what the manuals calls for and I am too lazy to look it up for you.

I love your sense of humor Don.

Many manufacturers recommend changing at least every 60K miles. I've never let mine go that far. I change mine about every 30K when I do the trans fluid. (but I don't tow much)