Muncie 4 speed oil
 

Is anyone here using the Brad Penn "Classic" Multi-Purpose GL-4 80W-90 gear oil in their muncie 4 speed transmissions, part # 7729 ?
I have GM #10953477 GL-4 oil in now but I think its starting to get a little harder to shift.
Thanks.

haven't tried the BP, but have had great luck with Sta Lube GL4.
http://crcindustries.com/auto/?s=SL24239
you can get it at napa.

Add 4 ounces of STP oil treatment and it will make it slick and for you northern guys it will also keep the oil from freezing up on those brisky winter days.

I used Red Line MT90 fluid, good stuff. Red Line makes some great products.

http://www.redlineoil.com/product.aspx?pid=46&pcid=7

I have purchased the Brad Penn oil, thanks for all the replies.

just curious, but how will stp oil treatment keep the oil from freezing up? that stuff is worse than molasses even on a warm day, when its cold its practically unpourable. i realize 4 oz is a small amount in the trans but how can it "help" the oil from congealing when cold? if anything the thicker viscosity will make the oil even thicker. one would assume anyways....:confused:

X90 LOL

Have used the Red Line stuff for years with great success in MT Transmissions and Rear Axles.

Tom Vaught

I use Mobil I 75W90 in my Muncie. Works smooth as butter. When my '64 was new, I complained about hard shifting in winter weather. The dealer put Dexron in place of the gear lube in the 4 speed. Worked OK, but I was nervous about wear. Can't say there was any evidence of a problem with ATF, though.

An old mechanic told me about the STP over 40 years ago. I had a 55 Ford 3 speed and that tranny would freeze up around 0 degrees. I had to back it in at nite and put it in first then drive 5 minutes in first before I could shift into second. He told me to just add 4 ounces to my tranny and I would be fixed. It worked it did not freeze and it shifted easier through the gears in any weather. I dont put it in my engines but I put it in every tranny I have had since then new or old.

Been using Wolf's Head 85/90wt plus STP in my Muncies for years. :)

Being here in Pa. winter is on the cool side , had the 64 out the other cool day trans. had a slight whine for about 2 /3 minutes then went away [ may have warmed a bit } still shifted nice , have standard 80w90 in the box summer trans. was flawless . Now the cooler temps. are here would like to try something like ATF in it . Any input from using ATF would be appreciated . thank you

This works well, there may be better stuff made nowadays, but I always used STP in my Muncies years ago and they shifted very well. And by the way I lived in Erie PA and it works well in the winter too as it clings the the innards after use and stays on while it's parked. The recommendation is 10% of STP added to your regular lube.

If you've never done the screwdriver test with STP you should try it. Dip the end of a flat bladed screw driver in any oil or lube and pinch it between your fingers and try to hold onto it. If you have any strength in your fingers you will be able to suspend the screwdriver without any problem. Wipe the blade clean and try it with STP and I have never seen anyone that is able to hold onto it when coated with STP.

it must be about the lubricity of stp & not the thickness.

i assume stp would be ok for a ST-10 too? mine shifts into second a little rough when cold.

As I've said before in another thread--When my '64 GTO was new and I complained to the dealer that it was impossible to shift the Muncie when it was cold outside, they recommended (and put in) Dexron ATF. Worked great.

What's the downside?

Chrysler has used ATF in their manual transmissions for many years. In the late 70s I put a clutch in a mid 70s Dodge van and when I pulled the driveshaft ATF ran out. Thinking someone put the wrong lube in I checked into it and the dealer told me that was what was in there from the factory, I put ATF in it when done and it worked fine.

Many of the late model manual transaxles use either ATF or motor oil too.

There is probably no downside to it, I however have never done it and would feel a little unsure of doing it. I might just be overcautious though. Probably a good idea to get in touch with someone that specializes in manual transmissions in older muscle cars and get their opinion on lubes.