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TR2/3/3A TR3 Transmission Oil

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White79MGB

White79MGB

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Simple question that I'm sure has been asked many times - what oil do you all recommend for a TR3 Overdrive gearbox? I believe that the factory recommends 90 wt gear oil but I am unclear on this. My MGB used engine oil in the gearbox. Thanks, Tim
 
I have used Valvoline 20W50 (Racing) for 16 years in my gearbox/overdrive driving 94,000 miles. I change the oil every 5,000 miles.
 
[ QUOTE ]
I have used Valvoline 20W50 (Racing) for 16 years in my gearbox/overdrive driving 94,000 miles. I change the oil every 5,000 miles.

[/ QUOTE ]

That is what Don wrote and I read eight years ago in another forum like twas yesterday and that is exactly what I'm still using today. Also easily available at NAPA.
 
It's an interesting one this. The old manuals recommend Castrol GTX which at that time was 20/50. I used this on my old non-overdrive box and after some fellow TR enthusuasts gasped in horror I changed it. That was when I saw the small flakes of copper in the oil. Maybe that was cleaning out years of debris, but I now use EP90 and it works just fine. Although I have now fitted an overdrive box and the overdrive does kick in very suddenly. You have me thinking!
 
I'd read the article about the 30 wt. in the OD and it makes sense. I was unaware anyone used another weight in the 4 speed.
Don, and anyone, I have been using 90wt GL4 in a non OD box would you rec using the 20/50? I assume the racing 20/50 is non detergent.
I live in AZ and our summer is HOT would you rec a dif weight for the hottest months.
Interesting subject.
 
I used straight SAE 30 single weight oil without any additives or detergent for the first 80,250 miles in my TR3A and went through 3 lay shafts etc. Since my restoration I have used 20W30 Valvoline (Racing) and when I had to change a top-hat bushing in 2004, I also changed the lay shaft, but it was only because it was all apart.

I don't know how hot a transmission gets, but I would assume that the oil and parts in a transmission in summer in the northern parts of N.A. wouldn't stay much cooler than one in Arizona.
 
John Esposito rebuilt my TR2's transmission and A type overdrive in 2003. When completed, John sternly recommended the use of 30w non detergent from any of the "majors". The fluid is changed and the filter given a bath every other year. Now some 15,000 miles later there has been not a hint of a problem. If John would recommend kangaroo urine that is what I would use.

Lou Metelko
Auburn, Indiana
 
Don,
I have a small leak from the selector shaft area and have always thought that due to initial cold pressure issues so I'll try the 20/50 valvo racing when I get home in May (you said 20/30 in one response but I'm guessing a typo). Is that 'racing' available off the shelf?
 
You will find the "Racing" label on the Valvoline shelf next to the regular 20W30 oil. The colour of the plactic bottle is different too.

Lou - That's the oil I used for the first 80,000 miles and got those lay-shaft problems I didn't need and couldn't afford as a young student studying Mechanical Engineering.
 
Don,
What are you using in the diff? I've stuck with the 90wt Gl 4. Does the diff have any yellow metal similar to the tranny that requires the 4 vs 5?
 
The problem with the "yellow metals" only happens at high temperatures and except for racing, I don't think you would have a problem in a street TR diff. But I use the older GL4 anyway.
 
Hi folks,

20W50 motor oil (non-detergent) and 90W gear oil are practically the same viscosity. So, I think that's why they are pretty much interchangeable in the non-OD TR gearbox. Original manuals called for 90W gear oil, GL4 (to avoid damage to brass parts). GL4 is getting a bit hard to find, so 20W50 racing/non-det motor oil is a good substitute.

John Esposito's article is pertinent to OD-equipped gearboxes, specifically, and his expertise in this is something I'd tend to trust. His testing and followup inspections of boxes that have run on lighter (30W non-det.) oils for some time also show that the gearbox itself isn't very fussy about what's used to lubricate it, so long as the sulphates found in GL5 oils are avoided. (NOTE: Many *synthetic* oils seem make the TR gearbox more prone to pop out of gear and might best be avoided. Others like Redline's synth gear oil seem okay.)

The diff isn't all that fussy either, but there are higher pressures and more friction-generated heat in there (than in the gearbox) so personally I prefer to stick with a 90W GL4 gear oil that will have some modifiers appropriate to crownwheel and pinion mesh, etc.

The IRS diffs on TR4A and later are more prone to overheating and tearing themselves up, so can benefit from both good quality and increased oil volume (i.e. a diff cover with more capacity than stock and/or with a built-in or added guide to help sling the oil up onto the crownwheel). I'm pretty sure later TR6s saw some improvements in this area.

/ubbthreads/images/graemlins/cheers.gif
 
Alan,
Thank you for the very informed reply. I feel a little easier about using the EP90 oil now. Do you think this is fine for an overdrive box?
 
I used 90W in my last TR3....

The TR7 factory fill switched from GL4 to ATF sometime in mid-production. MOPAR always used ATF in their New Process four speeds...even behind the Hemis.

90W would have to have a vastly different pour point than 20W50...after all the 'W" indicates "winter" so a 90W would be 90 weight in the witer and 20W50 would be a 20 weight during the winter...

It's my observation that oil (brands, weights, usages) is the most mis-understood and one of the most hotly-discussed topics in our hobby.

Geez...Some people still think Castrol is made from the castor bean...
 
[ QUOTE ]

90W would have to have a vastly different pour point than 20W50...after all the 'W" indicates "winter" so a 90W would be 90 weight in the witer and 20W50 would be a 20 weight during the winter...

It's my observation that oil (brands, weights, usages) is the most mis-understood and one of the most hotly-discussed topics in our hobby.


[/ QUOTE ]
Not sure how much this will increase understanding. Alan's earlier statement is pretty close to correct.
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"20W50 motor oil (non-detergent) and 90W gear oil are practically the same viscosity. So, I think that's why they are pretty much interchangeable in the non-OD TR gearbox. Original manuals called for 90W gear oil, GL4 (to avoid damage to brass parts). GL4 is getting a bit hard to find, so 20W50 racing/non-det motor oil is a good substitute."
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***********The main reason for this apparent conflict is that SAE rated motor oils are viscosity rated at 210 degrees F, & SAE gear oils are viscosity rated at 100 degrees F.*******************

For example - A typical SAE20 would have a cold viscosity of 200 - 400 SUS at 100 degrees F & a hot viscosity of 45 - 55 SUS at 210 degrees F.

A SAE 50 rated motor oil would have a cold viscosity of 1000 - 1300 SUS at 100 degrees F & a hot viscosity of 85 - 105 SUS at 210 degrees F.

So a multi rated 20 - 50 motor oil would be around 200 - 400 SUS at 100 degrees F, & 85 - 105 SUS at 210 degrees F.

This compares to a SAE 85W rated gear oil which has a viscosity of 500 - 600 SUS at 100 degrees F, & 60 - 70 SUS at 210 degrees F.
D
 
I know I am digging up an old thread here, but I am so impressed with the way the Valvoline 20W-50 VR1 Racing Oil works in the gearbox and overdrive that I just wanted to say "thanks" to all who recommended it. Can't believe how much better it shifts, including the OD!
 
If you want better yet, invest in some Redline MT-90. It's specifically designed for synchronized manual transmissions, and works great IMO.

I ran 20W50 VR1 for many years, based on Ken & Herman van den Akker's recommendations. It works quite well, as you've noted, but the MT-90 is a step up IMO.
 
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