aaronz28

anyone know if it is safe to use the Synthetic Gear Oil in a Muncie?

i bought 2 quarts of the Valvoline Syntec 85w90 but it seems very liquidy as opposed to the old fashion conventional stuff.

any help??

Aaron

Donald #31176

If its rated GL-4 or GL-5 its okay. I presently am using Mobil-1 in a BW T-10 and it shifts beautifully.

midyearvette

some guys get away with it and some don't...it wont hurt anything but it may be a little noisy depending on the shape the tranny's in....

LSUvetteguy

Been running Mobil 1 in my 66 BB Muncie for about three years with no problems.

aaronz28

thanks,
the trans internals are all new... Autogear M22w... the wide ratio with the M22 helix angle... everything is new and tight..

just wanted to be sure.
thanks

aaron

Donny Brass

don't be putting that stuff in my numbers matching M20.... it needs the dino residue to maintain NCRS points........

aaronz28

dont' worry... I bought some Used Gear Oil on ebay that was taken from a wrecked 1966 BigBlock car.... that way, everything stays original...

i'm going to be pulling your box back out this week, and i'll re-spray the grease/road grime i cleaned off, so that it maintains originality for the NCRS judging....

A

Donny Brass

narlee

dont' worry... I bought some Used Gear Oil on ebay that was taken from a wrecked 1966 BigBlock car.... that way, everything stays original...

i'm going to be pulling your box back out this week, and i'll re-spray the grease/road grime i cleaned off, so that it maintains originality for the NCRS judging.

I just saved all that old stuff in case I want to put it back later.

CWPASADENA

Actually, I have been using Synthetic Gear oil in my Muncys, Richmonds and even my old flat head Ford Transmissions for many years But I use Redline 75-90 NS (not the regular Redline 75-90 gear lube) which is speciffically designed for transmissions with blocker rings. If you use any oil that is also designed for rear axles, it will almost always hace the "slip" additive in it for the limited slip clutch packs which does not allow the blocker rings in the transmissions to work nearly as well. I think the GM Manual transmission oil also does not have any "slip" additive in it.

Synthetic Oil shifts easier when cold and the old Ford Transmissions really do work a lot better as they do not have big enough blocker rings in them. The only problem that I have found is the stuff will leak if all the seals and gaskets are not real tight.

Try it and see if you like it. If not, it is not the end of the world and you can always change it. You may be supprised.

Chris, CWPASADENA

wmf62

i presume the NS stands for something like No Sulfur, as sulfur seems to have a deleterious effect on brass parts (like synchro rings).

FWIW,,, when using standard trans lubes, make sure that it says MT on it, that makes it safe for brass parts.
Bill

PS: i understand Ford uses kevlar synchro rings in their trans, i wonder if there is a better synchro ring material for GM trans?????

CWPASADENA

:o

I should have been more specific. "NS" means "NON-SLIP". Redline 75-90 NS does not contain the "slip-additive" found in lube for clutch type limited slip differentials.

Chris, CWPASADENA

GCD1962

Autogear recommends GL5-MT in the spec sheet sent with the trans. Says NOT to use synthetics because of the synchros. I'd give George at Autogear a call before you pour anything in.

BarryK

for what it's worth, back in the spring I had the original M21 from my '65 rebuilt. The rebuilder specializes in Muncies and has a great reputation (Ed Hartnett in Pa).
When I got my unit back he told me NOT to use synthetic gear oil - just regular 80w-85W-90 gear oil

Dan Hampton

Most Ford Toploader professional rebuilders will tell you the same thing. The synthetic has too much lubricity and, as such, the brass synchro rings will not work effectively as a cone clutch when engaged by the synchronizer. A certain amount of resistance is needed to slow the gear for engagement.

DansYellow66

This proobably won't help any but I've been running synthetic lube in my Muncie for about 10 years. No apparent harm or problems - except I've noticed the skin of the aluminum case has taken on a permanent sheen apparently form the lube soaking in(????????). It does occassionally drip a drop or two at the rear yoke but that is probably due to some wear on the yoke. But, I bought a gallon of GL-4 lube the other day and I'm thinking of draining out what's in it now and going back to the old dino stuff - mostly due to advice on this forum.

Dan

CWPASADENA

Dan,

This is EXACTLY why Redline specifically packages an oil for brass blocker ring transmissions. (75-90 NS). Synthetics are "Thinner" when cold then convential gear lube which allows the Blocker rings to work much better when the lube is cold. How many miles do you have to drive your car before the transmission lube is really warmed up?

I think the reason most rebuilders do not specify Synthetics is because most of the 75-90 Synthetic gear lubes have the "Slip Additive" which is not good for brass blocker rings. In such a case, the brass (clutch) blocker rings want to slip and do not properly clutch with the mating cone surface on the corresponding transmission gear.

If a person wants to use convential oil, be sure to use gear lube WITH-OUT the slip additive.



My opinion and my experience.

Chris CWPASADENA

GTR1999

You might want to see if there are any part warranties you will void if you use other then the oil they spec for it. Me,all I use a 90 wt gear oil in the Muncies and ST-10's I rebuild and have in my cars. Works fine.

LSUvetteguy

I was told about the same my the guy who rebuilt my muncie. He said to try Mobil 1 if I wanted too but I could grind the synchros with high RPM shifts. I started slow and worked my way up the RPMs and never had a problem with scratching. Now I have complete confidence with any shift at any RPM. On the flip side, I don't know what benefit the synthetic actually offers in a tranny.

CWPASADENA

THEY SURE WORK BETTER WHEN THEY ARE COLD!



Chris, CWPASADENA