Originally Posted By: mjk
Let's hope their gear lube is as robust. Switching over both diffs this spring (got a great deal on 5 quarts).
Originally Posted By: Turk
I got the 2003 Sierra with the same 4L60E Transmission with 200,000+ miles.
I pull a 3,000 pound trailer A LOT & back it up a steep driveway, COLD, a lot.
Had a couple fills of Amsoil ATF in it for 150,000 miles.
Not one single issue. Highly Recommend the Amsoil ATF.
Amsoil makes a great gear oil. Second only to redline.
Op. If this is the first transmission service I suggest Maxlife. Do a few drain and fills to clean out the crud,driving a couple thousand miles in between drain and fills.
I have 3 of these trucks. 2 99s and a c3. 2 have a 5.3, the c3 has a 6.0 and a tougher transmission.
Once you get everything washed out then find the transmission oil your going to stick with. Otherwise you spend big bucks on that stuff only for it to get contaminated quickly and requires draining.
The more I abuse these trucks the more I'm impressed with just how tough they are. The first gen 5.3/6.0 nay have piston slap but that's the only flaw,if you can call it one.
They are easily as durable as the 350 they replaced. They get better mileage. The spin up quicker and in my experience require nothing more than periodic regular maintenance.
Anyways happy driving. Great trucks. Not complicated and very durable.
