67IHC

I have a Getrag360 behind a 1st gen Cummins 5.9L that operates fine, but is very chatty down the highway and can clatter also when getting into gear. It has 4.5 quarts of 75w/90, GL-4 Red Line MT-90 w/ some Lucas oil treatment in for good measure. Not sure the Lucas actually helped, as it was quieter without. Many on this forum and others suggest lighter weight oils to make sure all the bearings and synchros get properly lubricated. I hear folks say 15/30w works best and that w/ Lucas it works even better.

Love to quiet down this transmission and honestly make it shift a bit smoother. Is MT-90 the best way to go?

edwinsmith

I use 10W30 motor oil and I overfill by a quart which helps quiet things down a bit. The way to quiet them down however is to make sure the preload of the tapered bearings is correct. Too loose and they rattle.

cougar

FSM says 5W30 motor oil. I ran 15W40 in my 91.5 same as in my engine. Ran a heavier weight because I was always towing something heavy.

67IHC

This seems to be the most consistent recommendation - lighter weight oil makes it throughout the entire transmission. Is there a specific brand of 10W30 you like best for transmissions? Is synthetic better than regular in this case?

oliver foster

I run Mobil 1 5W-30 in my Getrag transmissions.
I over fill a QT and often install a finned cooler plate on one of the PTO holes.

I have heard from people I know, that tow heavy or live in very hot areas that run a 10W30.

I would get that thicker oil and Lucas product drained and refilled, if it where my truck.

BHD

I run 5w30 Mobile 1, overfill with 1 quart. I tow heavy with more mods than the G360 was meant to handle. The only problems I have had with the transmission is incorrect preload on the taper bearings. These transmissions need to be set up tight or they will make noise and fail.

My tow rig shifts hard on the 2-3 upshift and 4-3 downshift. And they all seem to rattle bad with low engine rpms.

67IHC

Originally the transmission had something like 5w30 init and was very loud. Then the RedLine MT which quieted it down a bit but I think adding Lucas oil treatment strangely made things worse. Now I'm thinking of the slightly lighter MTLV version of Redline as it might help with getting it to the top of the case. I appreciate the pre-load idea folks have suggested but I can" remove the transmission right now as it's my work truck.

oliver foster

Adding really thick oil like Lucas to a transmission that wants a very thin oil for proper lubrication, as you say, has been known to "strangely made this worse."

I am afraid the desire to quiet down the noise by using thicker oil, might not be helping out your transmissions overall health.

67IHC

I've been wondering about this. But overall the transmission preformed just fine. Certainly no Lucas this time around.

u2slow

I have been running 5W50 synthetic Castrol for over 10 years.

67IHC

And throughout this time your tranny has been quiet and shifts smoothly etc.? I might actually try 5W50 first but I have to find a new gasket kit since I can tell I have some seepage coming out the rear shaft.

Oran

Just bought my 93 w250 this past Friday, contemplating rebuilding the leaking 205 and 360 myself or buying the kits and paying a shop to do the rebuilds. Can anyone point me in the direction of a trans shop near st marys county that can actually be trusted to do a good job without robbing me?

oliver foster

What State is St Mary's County in?

Oran

South Eastern Maryland. My bad, for some reason I thought that this forum was kind of targeted to the greater Maryland area.

u2slow

Yes.