02-24-2019, 02:17 PM
I have been reading it's best to change the trans gear oil on a rebuilt manual trans at about 500 miles to remove any metal particles and assembly lube. Then I read you should only use a gear oil with a GL4 rating and not the more current GL5 rating. Apparently GL5 with cause excessive wear on soft metal parts like the blocker rings and thrust washers. I have been using Lucus gear oil that states it meets both GL4 and GL5 ratings. So any thoughts on this topic????? It's not easy to find gear oils with only a GL4 rating. I have found one from Joe Gibbs Racing at Summit Racing. Everything in local in parts stores is GL5 or combined GL4 and GL5 rated.
On another note for those of us with Traction Lok differentials or any other clutch type posi rear axle. A GL5 rated gear oil is apparently slippery enough to not need a friction modifier additive. I can at least say the Lucus gear oil I am using works just fine in my 9" Traction Lok differential without any other additives.
On another note for those of us with Traction Lok differentials or any other clutch type posi rear axle. A GL5 rated gear oil is apparently slippery enough to not need a friction modifier additive. I can at least say the Lucus gear oil I am using works just fine in my 9" Traction Lok differential without any other additives.
![[-]](https://mach1club.com/images/collapse.png "[-]")
