sb69coupe

Tom454 just finished up "helping" me rebuild my tranny and I owe him some public praise. The tranny looks great and he really went above and beyond. Thanks again Tom!

So, what type/brand of lube is best for a rebuilt Muncie 4 speed? Are synthetics OK to use, or should I stick with good old standard dino based stuff? Tom was using Valvoline but I don't recall whether it was standard or synthetic.

Pics to follow,
Shannon

mvftw

I just bought Castrol 80w-90 dino. Synthetic maybe good for a rebuild, but Not for an old one like mine.

Larry B.

Make sure you don't put 90W140 in or you won't be able to shift it when it is cold. I had to drain and refill mine after I put in some valoline that was too thick.

mrvette

MY '72 muncie was bought with the car and shifted like hell, just plainly rough and hard between gears, and in winter it was awful....

all I did was drop the fluid and replace with 15-40? Mobil ONE engine oil....
shifted like a charm, winter or summer, slicker than snot on a brass doorknob....never hung us, never missed a shift, the shifter felt like it was on silk....later on I washed out the shifter mechanism, and then oiled with the same synehetic oil....further nice improvement....

believe me...just try it...you will be amazed, and it lasted over 2 years of daily driving,,....and when it was sold Darryl of Darryl's 4 speeds couldnt honestly find anything matter with it....so I know the oil change out is good....

GENE

Rockn-Roll

I've rebuilt mine a couple of times and used Pennzoil or Valvoline 80W-90 GL-5...shifts smooth and smells great! But, You should ask Tom what he used so that the oil will be the same as the one he used to prelube the bearings.

A C

I use Valvoline 90w gear lube. It's worked great. The only thing I can complain about is having to squeeze it in on a nice 30 degree day with a lil 1/4 inch hose. It took me and my dad and four sore forearms to get that thick stuff to go through that little tube. :D

AC

Jvette73

Ide recomend the Mobil1 synth gearoil.

mountainmotor

I use and recommend the Chevron 80/90 gear oil. It gives a load rating of 75 lb on the Timken test where some of the others are a measely 50 lbs or so.

Red69

Where is the FILL hole on a muncie?

Larry B.

Passenger's side about half way up. It's a square plug. Use an eight point socket so you don't round off the corners. Get one for the diff while your at sears. When you need it, you've got it.

73 LS-4

I've had good luck with the Mobil1 75w90 gear lube in mine. All my buddy's always praise about how smooth my trans is.

:cheers:
Pat Kunz


[Modified by 73 LS-4, 10:17 AM 5/11/2003]

Steve Straus

I use Amsoil Synthetic 75W90 in both my diff and my M-21. Neither leak since they've been rebuilt. I used to get metal shavings out the wazoo when I drained them, but now the oil is clean as can be, a little shavings here and there, but I'm pretty sure that's from break-in. I'm not sure that the tranny or diff are any "smoother" because of the oil, rebuilding both of them certainly helped.





[Modified by Steve Straus, 12:23 PM 5/11/2003]

SAC

I remember reading in Hotrod or CC where they put synthetic auto trans fluid in a 4speed. I might be mistaking though. It was an article about adding synthetic to the tranny and rearend and they picked up 5-10 hp on a rear wheel dyno. Anybody heard of this?

Eddie 70

I put Mobil 1 in mine. Same in the rear diff.

Rockn-Roll

Gear lube is not all about lubrication. Part of it's job is to cushion the contact between the metal parts...auto trans fluid does not have anything for this purpose as it's a hydraulic pressure fluid. In fact, the additive for the rear end enhances the buffering agent. Without this buffering the teeth will be encountering high force impacts and in time will fracture and crack/chip. So, yeah, you can pick up some HP by using a non-cushioning lubricant, but at the risk of damaging your gears.