Diesel Fuel In A Manual Transmission? A Quick Miracle Fix For Poor Shifting! 

Sometimes with new fluid it’ll “clean up” overtime, the diesel fuel definitely speeds things up though. You can always drain the trans and do the flush and then put the fluid back in!

If the transmission is already good I can’t imagine it would make a ton of difference, I thiiiink it made 1 6 speed I had shift a little quicker

Hmm I remember reading on the MT85 bottle that it was comparable with the NV4500 so I assumed that’s the one you’d want for the brass synchros

@HHK yes the nv4500 has the fiber synchros so that's the mt85 or mt90 the mtl is for the brass

I would not recommend it, or if you were to do it you’d do it 50/50. The trouble is with the torque converter and the amount of passages in the valve body and the trans itself it would be difficult to get all the diesel fluid out of the transmission. It would take multiple flushes. The best option would be to drain the pan, do a new filter, and possibly disassemble and clean the valve body manually. You could -maybe- drill and tap the torque converter for a 1/8th NPT plug to allow you to drain it completely, I have a couple torque converters with that done.

Damn! Well that’s a first Did you Jack it up to drain it all out?

@@Hazardous-Hotrod-Knowledge yea I did cause I dropped a razor blade when cleaning the top cover surface and pulled pieces of gear when fishing in there so I pulled the whole trans after to inspect. It was a piece of my 4th gear that has been in there since 1995-1996ish 😂 I think it’s just time to do synchros cause after the flush it’s hard to get into 2nd or downside to second