I need to top off my M20 with tranny oil before installation. The Guy who rebuilt it filled it half way to the side cover plate he said. Does anybody recommend a tranny oil I should use? It will be sunny day car only. thanks!

Something such as Redline MTL will work out nicely. Whatever you use make sure it is a manual transmission lubricant and not a gear lube (GL4, GL5).

Bob.

I do not rcommend running straight RedLine MTL in a Muncie, Sag, Top Loader or in BW T-10 series transmissions.

I would however run a good 90wt GL-4/5 and about half a quart, or a little more, of RedLines MTL to aid in shifting.......but not straight. The manufacturers recommendation is for 90wt and I'll second that recommendation. I have run straight MTL, but after awhile it takes its toll on internals.

Back in the late 80's and eairly 90's when it was just making itself into our market, we ran MTL in the Muncie's and figured out that it needed to be changed about four times as much as a standard crude or parafin based oil....no matter what weight was required.

A suggestion to add to the others mentioned here. Before installing trans into car, push to the rear the cluster shaft shaft from the bellhousing mounting surface.

Clean the newly created bore with lacquer thinner or Brakleen and let dry. Fill this new bore with RTV and let it set & cure. This will prevent an oil leak later in its life, at least from this point.

FWIW, I have used Mobil 1 synthetic lube in a manual trans and it was smooth.

I have been using RedLine MTL in my Super T-10 for the past 10 years and have had ZERO problems with it or the transmission.

Last summer I had the transmission disassembled to install a nodular iron mid-plate (for added strength) and all the internals looked brand new, bearings and all! I think I could have re-used them.

I have tried other gear lubes (standard crude and synthetics) and the MTL provides much smoother shifting then any that I have used.

Originally posted by Everett#2390:
A suggestion to add to the others mentioned here. Before installing trans into car, push to the rear the cluster shaft shaft from the bellhousing mounting surface.

Clean the newly created bore with lacquer thinner or Brakleen and let dry. Fill this new bore with RTV and let it set & cure. This will prevent an oil leak later in its life, at least from this point.I have a newly rebuilt M20 ready to go in when my 302 is done. I tried to push the shaft back, but it only went maybe 1/64. Is this correct? Should the whole end of the shaft be filled with rtv up to 1/64" thick? Thanks for the tip.
Gary

GM recommends a 90 weight oil for the muncie. That is what I use and recommend.

Dave

GaryL, 1/64 inch depth is enough. You can fill the whole void and let it cure overnight before installing, or you can place a bead about the chamfer of the shaft end and the case.

Either way, as long as the RTV contacts & cures hard.