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gear oil in transmission

Posted by jshepard77 
jshepard77 Avatar
jeremy shepard
Maine, USA   usa

I changed the transmission oil on my '78 MGB last night. The oil I drained out smelled of gear oil, not regular 20W/50 oil. You know how gear oil has that distinctive smell? It smelled like that.

I'm not all that surprised, since I would have expected to put gear oil in there, until I read that MG's use 20/50 oil. So I bet the previous owner just put some in there.

Would gear oil in the gearbox cause any big issues? Car has always seemed to drive and shift OK before, and I haven't had a chance to test it out with the new oil. Is there anything I should keep an eye out for?

Not that it matters much, all I can do is use the right oil and maybe change it again in a hundred miles or so. I'm just curious if there are any bad side effects that could pop up later.

One interesting thing that I noticed as I got the car out of storage a week or two ago...with the car running and in neutral, if I let out the clutch the car would want to go forward a bit. Not like it was in gear...just wanted to drift forward. I guess that must have been from the heavy oil in the transmission. That effect seemed to go away after driving a bit.



1945 Willy's MB
1972 VW Beetle
1978 MGB
1979 Corvette
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cfrantz Avatar
Chris Frantz
Mississippi, USA   usa
1957 MG MGA
1964 MG MGB

Sulfur gives gear oil that particular odor. Gear oil contains additives to combat the high contact pressures seen in tooth contact areas and sulfur is one of the chemicals/elements that has been used for years (over a century?).



Edited 1 time(s). Last edit at 04/01/2011 07:53AM by cfrantz.
Ralph 7h Avatar
Ralph Siebenhaar
Viersen, Germany   deu

There is nothing wrong with gear oil in the transmission of a MGB. Although manuals say 20W50, the official British Leyland workshop suplement for the BGT V8 says gear oil for the V8 although they share the same internals and are only different in the bell housing and some ratios.
BTW, the V8 was delivered with OD only.
In my Roadster, I tryed gear oil many years ago (1978 mod. OD gear box fitted) and have not had any issues since.
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kellybell Avatar
Kelly bell
Atlanta, USA   usa
1972 MG MGB "Mr B"
1975 Porsche MGB
2000 Volvo S70

I have always put gear oil in my gearbox - no issues.
twigworker Avatar
Jack Austin
Blowing Rock, NC, USA   usa

Always a big deal debate on this.

One side says 30wt non-detergent motor oil because it is safe for brass things inside.

One says gear oil for the pressure qualities for the teeth themselves.

Another advocates multi-vis motor oil because they think that it gets to the bearings and gears faster.

Still more want something to use any sort of motor oil because it flows through the OD passages easier.

Some car manufactuers spec motor oil and some spec gear oil for each of their transmissions and ODs when they have essentially the same innards.

To each his own, but for me any of the motor oils will do just fine as will the gear oil. The only exception might be that in very cold climates I might lean toward motor oil simply because it bothers me to think of the really gooey stuff being forced through the OD pump and valving when it is twenty degrees.

Jack



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balloonfoot Avatar
Lloyd Faust
Southlake, TEXAS, USA   usa

Factory service bulletins say gear oil is fine.



“Better to remain silent and be thought a fool than to speak out and remove all doubt”.
- Abraham Lincoln

"Anyone with an intense emotional interest in a subject loses the ability to observe it objectively: You selectively perceive events. You ignore data and facts that disagree with your main philosophy. Even your memory works to fool you, as you selectively retain what you believe in, and subtly mask any memories that might conflict."
jshepard77 Avatar
jeremy shepard
Maine, USA   usa

Great info guys...thanks.

I did notice that the car did want to creep forward with the clutch out in neutral. I'm in Maine and it's been in the 40's, so perhaps that cold temp was making the gear oil really viscous and causing the car to creep. It will be interesting to see what the 20W/50 that I put in does. But, we got 4 or 5 inches of snow last night...so that test will have to wait.



1945 Willy's MB
1972 VW Beetle
1978 MGB
1979 Corvette
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Robert Kirk
Davenport, Iowa, USA   usa

I don't think modern multi vis oil would harm a gear box but i doubt it is any better than non detergent straight 30 weight. Just doesn't make a lot of sense to dump in a load of engine additives into a transmission unless they share the same oil bath ala Series A Minis.
The only "debate" I have run across is some feel the grease doesn't allow the synchros to work as well as they should.

I'd rather talk about who has the cutest grand kids than debate best oil or gasoline...because I already know the winner of the grand kids debate devil smiley



Regards,
Robert Kirk
kirkbrit@yahoo.com
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bills Avatar
Bill Spohn
W. Vancouver, BC, Canada   can

In reply to a post by kirks-auto The only "debate" I have run across is some feel the grease doesn't allow the synchros to work as well as they should.

Yup, and one other - use gear oil, or indeed anything thicker than a straight 40 wt. and the OD doesn't function well until the gearbox warms up.

You can use hypoid oil, engine oil or even automatic transmission fluid (as per BW T-5 specs) pretty much interchangeably in most manual gearboxes.



Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1969 MGC roadster (175 bhp), 1957 Jamaican MGA (200 bhp)
1965 Jensen CV8 (375 bhp), 1971 Jensen Interceptor (350 bhp)
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
West Vancouver BC

Proudfoot Avatar
Mark Stoltzfus
Amish Country - Ohio, USA   usa
1980 MG MGB ~ For Sale ! ~

Here is a link to a short article written by someone who works on them though it is more overdrive specific. I thought it was a good read. http://www.quantumechanics.com/categories.php?op=newindex&catid=11



Edited 1 time(s). Last edit at 04/01/2011 11:00AM by Proudfoot.
BobG Avatar
Bob Gohn
North Andover, MA, USA   usa
1969 MG MGB
1977 MG MGB

Don't forget ATF in OD gearbxes on the list of debates / alternatives. Using it fixed my OD sticking issues, though I'll probably switch back to 30W or 20/50 oil.

FWIW - do look at the Quantum Mechanics test data for ODs. While I don't think this was conclusive on 30W NT vs. regular 20/50, it did seem to have some interesting justifications re: NOT using some other alternatives....

Bbo
ingoldsb Avatar
Terry Ingoldsby
Calgary, Alberta, Canada   can
1971 MG MGB

First of all, the viscosity ratings for engine oil and gear oil are different. 20w-50 engine oil is about the same viscosity as 80w-90 gear oil.

There are concerns with GL-5 rated gear oils - sulphur compounds that can hurt brass components - but I think the brass components were only used in early transmissions so that is probably not a problem for you.

This weekend I am changing to Redline MT-90 75w90 GL-4 gear oil. It explicitly states that it is safe for brass synchros. It also claims to optimize the coefficient of friction for synchros.

I question the 30w recommendation given by Quantum for OD transmissions. As far as I can tell, Quantum did not take into account the effect of temperature on 30W oil. It performed better than anything else they tested at one temperature. I would be interested to see how 30w oil would fare at temperatures below 0C (32F). Multi-grade oil is actually constant viscosity (or close to it). So it performs the same over a range of temperatures. If you live in California, the 30w oil probably works great for you. But if your car must deal with a wide range of temperatures use multi-grade. BTW - the factory recommended different multi-grade oils for different temperature ranges.



Terry Ingoldsby
terry.ingoldsby@DCExperts.com
bills Avatar
Bill Spohn
W. Vancouver, BC, Canada   can

Terry, I'd add only that one should beware of using synthetic on OD transmissions, especially if you use them hard. I've seen several trashed OD units because of that. Otherwise, though, I really like the synthetics - it almost always give superior synchro action.



Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1969 MGC roadster (175 bhp), 1957 Jamaican MGA (200 bhp)
1965 Jensen CV8 (375 bhp), 1971 Jensen Interceptor (350 bhp)
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
West Vancouver BC

Proudfoot Avatar
Mark Stoltzfus
Amish Country - Ohio, USA   usa
1980 MG MGB ~ For Sale ! ~

I would like to use the Redline oil too but I'm concerned about leaks. Now that I have replaced some seals and gaskets, if it holds 30W maybe I'll try the Redline after while.
Robert Kirk
Davenport, Iowa, USA   usa

In reply to a post by BobG Don't forget ATF in OD gearbxes on the list of debates / alternatives. Using it fixed my OD sticking issues, though I'll probably switch back to 30W or 20/50 oil.
Bbo

ATF is a powerful cleanser...don't know but suggest that may be the reason your OD stopped sticking. A lot of folks get het up about Marvin's Mystery. I sorta think I solved the mystery and use the not patented version with pretty much the same results.



Regards,
Robert Kirk
kirkbrit@yahoo.com
563 323 1017
Moss distributor UK importer
Beat or match any retail/delivered quote

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mac townsend Avatar
Fairfield, CA, USA   usa

Your car came with gear oil in the transmission. They changed the recommendation in a TSB issued to dealers about the time of the RB cars; not that the RM transmissions were any different, it just took them that long to do it.

The manuals were never changed (not the only instance of that!<G>winking smiley



1973 Pale Primrose Roadster. A nice 10-footer!
SUs, Datsun 5-speed
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Jim K Avatar
James A. Krasnansky
Liberty, KY, USA   usa
1970 MG MGB GT "Chloe"
1971 MG MGB GT "Roscoe"
1972 MG MGB "Camilla"

What has been said - don't panic about it.

A while ago, there was someone who wanted to use gear oil in the engine. Not a good idea.



Jim K is a grease-stained wretch
balloonfoot Avatar
Lloyd Faust
Southlake, TEXAS, USA   usa

In reply to a post by mac townsend
The manuals were never changed (not the only instance of that!<G>winking smiley

Actually the late workshop manuals do call for either 20-50w OR 80w gear oil. In SoCal, we always used gear oil....now if you have an overdrive and its -20F outside....might have some issues....but above 32F...forgetaboutit.....



“Better to remain silent and be thought a fool than to speak out and remove all doubt”.
- Abraham Lincoln

"Anyone with an intense emotional interest in a subject loses the ability to observe it objectively: You selectively perceive events. You ignore data and facts that disagree with your main philosophy. Even your memory works to fool you, as you selectively retain what you believe in, and subtly mask any memories that might conflict."
RAY 67 TOURER Avatar
Ray Marloff
Fort Bragg, CA, USA   usa
1967 MG MGB "My Girl"

I used gear oil for about 6 months and the only difference that I noticed, from engine oil, was that the transmission was very hard to shift when cold. I've gone the 30W non-detergent route and couldn't be happier. Chris Betson, of Octarine Motors in England, visited the company that now owns all of the Laycock De Normanville tooling and asked their opinion on what oil should be used. They told him that anything from ATF to gear oil would work in their units. RAY
Robert Kirk
Davenport, Iowa, USA   usa

In reply to a post by balloonfoot
In reply to a post by mac townsend
In SoCal, we always used gear oil....now if you have an overdrive and its -20F outside....might have some issues....but above 32F...forgetaboutit.....

Actually if the temp in SoCal dropped that low I suggest there would be more worries than the weigt of the lube in the tranny....devil smiley



Regards,
Robert Kirk
kirkbrit@yahoo.com
563 323 1017
Moss distributor UK importer
Beat or match any retail/delivered quote


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