The Pennzoil Syncromesh meets the same GM spec as the GM Syncromesh HPmike posted but cheaper.

I've used the Passon gear lube and it works well too.

I run the royal purple gear oil in my a833 and my dana 60 with no problems at all.


If I start to have problems i will blame it on this post.

This is why I posted using the correct synthetic lubricant for the application.
There are various syncromesh fluid out there that work well in a manual trans.
Check out the MTF Synthetic Synchromesh trans fluid.

Most leaks that occur after changing to synthetic are due to the change, not what it's changed to. If aged dino were replaced with fresh dino lube the leak could just as easily occur.

I've successfully used synthetics that were formulated for synchro in older T-10's and 833's with vast improvement in shifting; especially when cold.

For the record my trans shifter fine it just leaked for whatever reason. I have a fresh trans that has had synthetic manual trans oil since day one that has been fine.

;Should have been more clear on that.

Apples/oranges here-but-

Royal Purple Synchro works great in the TKO.
I have not touched the Dana EVER and have owned the car 20 years. Could be the original [Edited by Moparts - Keep it clean] in there. I'll bet it is.
Since when is g o o k in need of an edit?

Have a read at this article.

...and that is basically why I went to Redline MT-90 I wanted a synthetic lube that would not degrade the performance of the synchros. Of course it has to be GL-4. But I did not expect a leaker. Again, we've all heard of engines leaking more with synthetic, I just didn't figure a 833 was much of a risk for the same (apparently was wrong).

I will try a dino GL-4. Engine oil? Don't hear of many people doing that.

You didn't say where it was leaking.
I use MT-90 with no issues at all. Runs great.
There are a few things to keep in mind, when you re-build an A-833 tho.
#1 Most of the newer brass synchro rings have six oil slots on the inside. The original Mopar ones had three. If you are using the newer ones, you may have trouble. Those oil slots throw off too much oil on your gear races, plus they are weaker than the original 3 slot synchros. That is the first issue I see as a potential problem.
#2 Leaks can occur on the side cover shift lever seals. I had Liberty Transmissions modify mine with positive oil seals (no leaks).
#3 Run a thin strip of high temp silicone sealant on all case gaskets (both sides), to ensure they don't leak.
#4 Alway's replace your reverse switch gasket...it will leak if old.
#5 Check your tailshaft vent to ensure it is not stuck shut. If stuck, it will cause excessive pressure in the case, and possible leaks. Same vent is found on a 8 3/4" axle.

The single biggest sources of leaks in an A833 is through the reverse light switch. When the oil level is below the switch there is little or no leaks, change the oil and fill to the proper level and the oil level will be above the switch and just dribbles through the switch until the level is below the switch. This is especially apparent when you leave the tranny in reverse when its parked.

The oil will run down the side of the case and be blown back making the rear slip yoke look like its leaking. Because of the proximity of the switch to the junction of the tail shaft an main case the leak appears to be there and it will run over to the reverse gear shaft making it look like its leaking.

So before blaming the lube make sure its not the switch. Brewers has a redesigned switch that provides for a much better internal seal.

I have had dino gear oil in my A833 and it shifts stiff. I have had ATF in it and it shifts good but has a lot of gear rattle in neutral. I tried Mobil 1 synthetic gear oil and the syncros didn't like it and I got a lot of clash. Most recently I tried Pennzoil Syncromesh fluid and it shifts great.

I am a great proponent of synthetic lubricants. My Mobil 1 experience only tells me that I selected the wrong fluid for the application. Mobil 1 has friction modifiers for limited slips diffs. This allows the clutches to slip in the diff which is exactly the opposite of what the syncros in the A833 want. My recommendation is if you are interested in using a synthetic lubricant in your A833 then it has to be one formulated to work with syncros.