Howdy folks i got thise 92 thats new to me and it has the GetRag tranny. I was curious what the heaviest lube i can run in it would be. I pulled up the factory spec on my computer at work and it brought up like 5w-30 motor oil. I dunno about ya'll but that seems a lil light for a 3/4ton and 1ton truck transmission I talked to a local tranny guy and he said he's familiar with this transmission and said i could run 90 weight gear oil. Anyone done this with no problems? Anyone know better than to do this and know what the heavist oil i can run is? just let me know thanks.

~Phil

 

i run gear oil, thats why they made it for gears but most every one else runs a synthetic and runs a quart over full, i don't with gear oil yet. they just shift a little harder than if it had synthetic in it, because gear oil has to warm up.

 

I run Royal Purple 75-90 MaxGear in mine and like said above, its just a tiny bit stiff till it warms up some, but I trust heavy weight RP oil with harsh treatment than I trust 5w30. I've read where lots of people have run a few hundred thousand miles with 75-90 in there getrags with no problems. Mine still feels like new and has no slop in the shifter.

 

Run 5W-30 synthetic motor oil.

 

5w30 synthetic. And overfill it by an extra quart. Mine is apart right now. before I put the top cover on I'm going to dump the oil in the top and see where it comes too in the case so I can make a good gauge for checking the level. The oil has to get in some small and tight places in the getrag thick oil might have a hard time doing. We will see how long everything lasts in mine after its freshening up.

 

I run 4.5 quarts of Wal-Mart brand full synthetic 5W-30 motor oil. I don't know if it was the change to synthetic, overfilling by a quart, or a combo of the two, but my tranny shifts a lot better now. Before my truck was hell to get in reverse, now it falls right in with a little pressure.

 

There are also lots of bearings in the getrag which would rather swim in 5w-30. I ran some regular 5w-30 for a couple hundred miles after I rebult my getrag, then flushed it and overfilled with mobile 1 5w-30 synthetic. Shifts much smoother and is a little quiter with the synthetic.

 

To tell the truth I dont care if it shifts like its mud LOL. I would just figure gear oil would offer more protection for a 3/4ton and 1ton tranny than a motor oil that I woudnt even run in a honda. Maybe thats just my opinion. So in other words theres no one who has seen concrete proof that its tranny suicide to run gear oil in the getrag?

 

i run red line MTL never had any problems

 

okay i bought mine with 228,000 miles on it, i was told it had a rebuilt trans but it didn't growld a lot in third at low rpm all with gear oil. and at about 240,000 i had to pull the trans because the first and second gear shift fork roll pin broke, at this time i re-shimed the bearings, no more growl, i have been towing most of the time with it about 11,000lbs and i have no problems except it shifts hard when cold. if they run gear oil in a semi trans and rear ends i will too.it now has 278,800 plus miles.

 

Well i appreciate all the help guys its really been a tuff one. Like i said buncha guys tellin me to run motor oil and theres a local transmission guy been in it for years and is familiar with these things told me to run gear oil so i been a bit unsure on this one.

 

i run mobile one 5-30wt quart and a half overfull.

 

Mobil1 5W30 overfill by one here, too.

 

Amsoil 5-30, overfill by one quart as recommended by the "membership"

 

i have a 91 using 15-40 amsoil 1 quart over full with 875,000+ miles on it pulling heavy