Lotus76

Im getting ready to pull the automatic out of my 76 and put in the 4 speed.

What Gear oil do you use in your Muncie? and Why?

Thanks for your input,

John

mvftw

75w-90

Jughead

No particular brand, Castrol or Pennzoil I think.

Sigforty

75w90 Mobil 1 here!

Solid LT1

Absolutely DO NOT! use Redline MTL as it is made for modern cars. Torco, Lucas and other 75-90W unless it is a M-22 that needs a "special" gear oil for it's gearset. I use Redline Shockproof 75-250 in my "Rock-crusher" but, synthetic seems to leak past the gasket technology of our Muncies (a very slight leak but after sitting weeks in the garage, a penny size pool can be seen.)

Garson

I talked to a couple of gear venders about oils this week. I am rebuilding my diff and had may trans done about a year ago. They all say to use a good grade of 80-90 gear oil and not the synthetic. They say that the way thier gears are made that dino oil works best. This came from 2 different manufactures of trans and rear end gears for the older cars.

Garson

GDaina

Mobil Synthetic in the 5 speed

5speeds

I'll probably get bashed on this one...

Regular 75-90wt from Valvoline or any other maker is fine. The Synthetics such as Amsoil and Redline seem to me to have great visability because they advertise and are promoted well. Yet no racers in Nascar use this crap. Let's face it, the average person will not put his transmission to the extreme abuse and heat seen in endurace racing. I don't want to get into the whole my oil is better than your oil schtick either. Several times I have seen both Redline and Amsoil turn to jelly , break down and separate. I've had better success with Mobil 1 and Royal Purple. This probably won't happen to you since your car won't be seeing the extreme end of this spectrum. Drag race stuff, same deal. I doubt anyone is running 8 sec 1/4 miles with a Muncie and need be concerned.

Muncies can leak with certain synths... sometimes because the nature of how the oil flows, shift fork wear can actually INCREASE. YET, for some people driving in colder climates, synthetics are neccessary.

Keep in mind, there are probably of bunch of people running Redline and Amsoil with great success or swear by some other brand. I'm just telling you what has worked for me.

Paul
www.5speeds.com

djcwardog

I have used Valvoline for years - no leaks.

BTW - Paul, any updates on the new Muncie 5-speed that is due this year?

pgtr

Probably

Well when you say 75W90 Valvoline - I presume you are referring to their synthetic GL4/5 gear oil. Interestingly enough that is what i've settled on too as my 2nd choice. My first choice is Valvoline 80W90 conventional GL4/5 gear oil.

The Muncie has always been a bit of a dilemma for me to arrive at a good lubricant for and one that I've been researching and 'watching' for a while now - when I saw this thread - just had to take a peak.

A) GM used GL5 SAE90 forever or GL5 80W90 nowadays(?). Let's be honest - these things lasted and lasted and lasted w/ this stuff.

B) It's a fact that their synchros are made from bronze - it's entirely possible and perhaps likely that a traditional GL5 can be corrosive over time. HOw much time I do not know.

C) Many many people have reported success w/ a GL5 in their Muncies. I've never heard a complaint and I've kept my eyes on Muncie lubrication threads for years now. Yes that's anecdotal.

D) Some people have reported problems w/ MT90 or similar. Again - yes that's antecdotal.

E) Definately a synth 75W90 is better during cold initial driving periods - but again let's be honest - how many C3s are seeing regular early mornign driving in a colder northern climate these days?

F) Yes, Muncies do sometimes tend to be 'leaky' given the wrong lube.

Essentially what I've arrived at for the Muncie (at least mine) is a conventional 80W90 (or maybe synthetic 75W90 if you really do deal w/ cold temps like sub 40F) gear lube that meets BOTH GL4 *and* GL5. That typically means a GL5 w/ it's respective EP additives that have been either buffered or fundamentall modified so as to be non-corrosive to synchros. The ONLY conventional 80W90 GL4/GL5 I am aware of ANYWHERE is Valvoline 'High Performance Gear Oil'. There are several synthetic 75W90 GL4/5s around I think - Valvoline and Royal Purple come to mind but perhaps others as well...


Well they are niche players better advertised in gearhead circles - C3s, old Datsuns, amateur racing levels, you name it - they are well circulated in these groups but in the mainstream they are NOT well advertised IMO.

Just because a product is popularly accepted in gearhead circles does not automatically make it good OR bad. Witness the crappy BFG Radial TAs that most here swear by... On the other hand some perfectly good legit stuff like Ford DOT3 brake fluid is well regarded in gear head circles too.

All I'm saying is that just because a given product is popular in the gearhead community does not automatically mean it really is good or better.


This is why I've gone full circle back to conventional gear oil for a Muncie.

Paul, when you say what's worked for "you" are you including the many Muncie customers you've had over the years? If so, that's a pretty powerful statement.

Appreciate your taking the time to post on this topic.

mrvette

Funny, I drove my muncie '72 here for a couple of y ears with just synthetic engine oil in it......shifted much smoother, and ran many a road trip like that, never showed anything unusual in leaking either.....but the shifting improved dramatically, amazing really, just for an oil change....

them old heavy weight gear oils are out now, hell even new trannies use ATF in them, sometimes....
with posi additive, I"m convinced rear diffs would be great with synthetic engine oil in there....

GENE

GDaina

Yup, running synthetic in the 5 speed, the diff and the 533...since 2001...no leaks, no rumbles...great shifting...

pgtr

The Muncie is perhaps the most lube tolerant transmission I'm aware of - it's amazing the kinds of things people can put in and report excellent results with. I've seen some older light duty transaxles recommend motor oils but it's been a number of years since I've seen this.

HOwever It's not particularly informative or amazing if you don't tell us the viscosity of the engine oil, it's service level OR what was in there before. Were you replacing a conventional motor oil w/ a synthetic motor oil in the Muncie?

1) Can you provide some facts that back this claim up now considering conventional 80W90 gear oil is is factory fill in plenty of current MTs.

What does a modern transmission given it's tolerances and different design constraints that runs ATF have to do w/ a 40 year old transmission?

Name us some of these MTs that that you claim run posi-track additive in the manual transmission fluid either as factory fill or recommended by the factory manuals (and last I checked the Muncie is not a transaxle so no, they don't count).

Perhaps even more interesting - explain to us what the value or purpose might in theory be for a posi additive in a manual transmission...

Dave62

Now you are beginning to get into some of our old race car tricks...we ran 10W in the tranny and rear gear on the 1/4 mile 30+ years ago.
Less drag..go fast..ran low 12's with a shoebox and a 265 CI motor..
Leaked like heck...and we broke so many parts we never knew if the lube was any good or not.
I have always heard......that the new synthetics in an old 4 speed would cause them not to shift properly as the brass rings would not grab to slow down the gears so they would mesh up properly during shifting. Probably just bull...but I still use 80W90.
Dave62

Fevre

I noticed mine shifted smoother after putting in Mobile 1 syn gear oil, esp the times I took it out in cold weather (<40 deg).

stingr69

Probably depends a lot on climate as to the particular wt you need to run. I have not found synthetic lube to be worthwhile in a Muncie personaly.

I have a low mileage factory Muncie that I have run dino 90wt in then switched to synthetic multi grade and it only seemed to slightly if at all improve the cold weather shift. It definately leaked faster but that is probably because of the lighter viscosity when cold. I will be topping it off with dino 90wt as it leaks out over time. I have a new rear seal ready to go in but I need time to get under there and change it out some day.

-Mark.

5speeds

Here is some of my experiance. Back in the mid 80's there was a boom in Amsoil and later Redline use. In circle track racers we noticed cracked synchro rings and worn forks consistant with synth oils. We went back to the conventional Valvoline HP gear lube with no problems. What was happening was that the synth oil lubed so well that the rings were chattering on the synchro cones and cracking. Oil tended to flow towards the back of the transmission on acceleration and flow off the forks faster, which can be above oil levels.

Again, this stuff would probably work well for normal use.

I sponsor several race teams. Some run Muncies some run our Enduro 5 speeds, some run the Rolteks and Jericos. These boxes are torn down and inspected every season end. We never got into recommending lubes but started to notice heat checking on gears with certain lubes.

Having several conversations with Leonard Long of G-Force transmissions who manufacture most of the stuff for Tex Racing including the new NASCAR single rail 4 speed, he confirmed these same problems. They have there own concoction made by Synergen for them ( G-Force GF2000 Lube). Most teams don't reveal what stuff or additives they run. I can tell you that switching to Mobil 1 cured the heat checking issues. Later we tried Royal Purple and the wear results on shift forks improved.

Here is a link to the Jaguar version of a race Muncie. Some of you vette racers may remember this car kicking everyone's *** last year at Watkins Glen and Sebring. Well now you know it was running a Muncie.

http://www.5speeds.com/racing/number3.html

Paul

Solid LT1

Paul, thanks for posting, I know how talented you are. I agree that the Lucas Oil Company "Synergyn" brand of gear lube is one of the better products out there (it is NOT a synthetic but rather a petroleum based lubricant.) I was looking at the Jag M22 build-up and noticed you don't use those "new tech" plastic caged bearings, I want to know if a standard Torrington part will install before I build my M-22 for my vintage Vette. I promise I won't "punt-off" any Jags in my race group if you tell me there is a production bearing that can be installed. Thanks, Eric B.

5speeds

That conversion was done by Liberty's High Performance. They bore the gear out, press the bearing in and remachine your sleeve. I've used the newer Autogear roller M22 1st gears as well with no failures....

The GF2000 oil is a Synthetic.

Paul

www.5speeds.com