This trans (even after rebuild with new synchros) has always been balky going into 3rd, and to a lesser extent 4th. It kinda hacks me off because I've driven several 1st gens that are running motor oil and they shift fine.

I broke it in on 5W-30 motor oil (which really sucked), then put in Redline MTL. That was an improvement, but it wan't great. I noticed that it shifted great when the trans was good and hot, like after an hour on the highway at 70+. When I found out that the RP Synchromax was even thinner than MTL, I decided to give it a shot. I just dumped it in this afternoon, so I haven't had a chance to try it dead cold. It's definitely better, especially on downshifts. The trans was warm but not hot when I drove it, and it was better than normal but not as good as I'd like it to be. I'll post an update on how it is when dead cold. 3rd is usually pretty balky until it's been driven for 10 minutes or so.

Anyway, if you have a Getrag that's being difficult, give this stuff or the Redline MTL a shot.

One caution: If you do heavy towing stick with Mobil 1 5W-30, the friction modifying additives in the trans oils that help the synchros grab will make the trans run very hot in 5th under a heavy load.

 

A lot of people use Pennzoil Syncromesh in high HP fwd/awd transmissions for shifting due to bad syncro's or 'notchy' shifting. Much better than Redline MTL and cheaper. In NC you can get it at autozone.

 

I am still running atf in my getrag with 300K miles on it, Only 2-3 shift may be a bit baulky until i've driven only 1+ miles, Downshift is fine though,, WHy is it that most here arent using atf in the rag, Isn't that what it calls for in the owners manual?
Also have a Benz with a getrag, And it too calls for atf.
Peter.

 

The manual says you can use ATF if the trans is difficult to shift in cold weather. Otherwise the preferred lube is 5W-30 motor oil. Of course, they also said that you never had to change the trans oil.

I never bothered with ATF because I figured it wouldn't make much difference. The Synchromax is the same weight as an ATF but has additves to help the synchros grab.

 

I myself am a beliver in mobil 1 5w-30, it's the bomb after I rebuild my trans I have had no problems. I over fill it a quart and 1/2 I change the trans oil ever winter. once a year more less. I pull a 25 ft protrack goose neck tailer lots. The protrack weighs 4700 pounds by it self, An around 16,000 with tractors and hay u name it's hauled it.

 

Hey wanna, I'm glad you gave the RP a shot! IMO there is nothing better in the oil world. I'm probably talking into the wind here but I think everyone should give their oil a try. It's hard to hear the difference in engine smoothness and quietness in our diesels with it, but I'm sure plenty of people are runnin around here that own gassers. To all people: Change oil in your gasser to RP and hear, feel, and see the difference. Engine will run quieter and smoother, free up some horsepower, and you will see an improvement in MPG guaranteed! Once you do this.... you'll believe in RP and want it in your first gen! I sound like an advertisement lol. Sorry wanna, didn't mean to hijack into a war

 

I to had switched to Mobil 1 last winter and was happy with the improvement......not shore what it was that i drained out of it thow

although it shifts well,...note real satisfied with it. I also planning on change it to Royal purple tranny stuff my self. But probably not till spring sense my daily driving chores will be switching to my 89 XJ this winter!.......although my diesel would still get better mileage!

 

So for that getrag that I'm rebuilding, what would you recommend breaking it in with and for how long?

 

There is better people out there then me to answer this question but here gos.......Being that winter is upon us Start with ATF or maybe 5w30. put 500 miles on it and then put the RP in.

 

I think 500 miles is a little short unless you run exclusively in town.

I would dump some conventional 5W-30 in, run it for 1500 or 2k and dump it to get out the worst of the glitter from the synchro break-in. That first change the oil will look golden. Then put your lube of choice in and change it every 30k.

 

Update on the cold performance:

Definitely much better. It was a little balky the first time up into 3rd, but a mile down the road I was able to make the 4-3 shift without double clutching.

I'd still like it to shift perfectly every time, but I am pleased with the improvement over the MTL.