Gearbox Oil-Which ones best??

[MR2Adam]

Having a service soon on my Roadster so I'm going to get the gearbox oil changed. But which oil is the correct one and which one is best?

Also, as my car is a 6 speed and has the LSD (I presume), does the oil need to have the additive for the diff?

[1979scotte]

I think most people go for mt90

[Bossworld]

Happy to be proved wrong but I think I read ours don't need LSD specific gearbox oil. If someone could confirm if we have a Torsen or Viscous Coupling that'd be handy.

Did a lot of research last year and apparently back in the day, GL-5 gearbox oils could trash brass synchros.

MT90 is rated GL-4 and very highly regarded in this community.

But you'll find a lot of modern gearbox oils are rated for both GL-4 and GL-5 - the brass synchros thing seems to be a legacy issue.

I'm running this

https://www.nielsencdg.co.uk/total-transmission-dual-9-fe-75w90-manual-gear-box-oil-tot-201656/

[shnazzle]

I've always stuck to MT90. Yes it's 35 quid but how often do you replace it? And the difference is quite noticeable if you've never replaced it so it justifies it in your head

As far as fluids go, I just go for the best. Saving 20 quid on something I replace maybe once or twice a year in case of engine oil, why scrimp?

[MR2Adam]

I've always stuck to MT90. Yes it's 35 quid but how often do you replace it? And the difference is quite noticeable if you've never replaced it so it justifies it in your head

As far as fluids go, I just go for the best. Saving 20 quid on something I replace maybe once or twice a year in case of engine oil, why scrimp?

Ah that's good to hear it will make the difference! I've heard Redline oil is that stuff to go for.

How much oil does the Roadsters gearbox take?

[Carolyn]

Happy to be proved wrong but I think I read ours don't need LSD specific gearbox oil. If someone could confirm if we have a Torsen or Viscous Coupling that'd be handy.

Did a lot of research last year and apparently back in the day, GL-5 gearbox oils could trash brass synchros.

MT90 is rated GL-4 and very highly regarded in this community.

But you'll find a lot of modern gearbox oils are rated for both GL-4 and GL-5 - the brass synchros thing seems to be a legacy issue.

I'm running this

https://www.nielsencdg.co.uk/total-transmission-dual-9-fe-75w90-manual-gear-box-oil-tot-201656/

Our diffs are Torsen.

[Ardent]

I went for mpm gear oil of the correct spec and veryhappy with that.
Mt 90 "might" be better. I dont know.
I have yet to see a review where 60 70 80 thousand mile used gear oil is dropped, replaced with something non mt90 ran for a few thousand miles then dropped again for mt90 and compared.
Is it because it is mt90 or is it because it is new oil that people say how much better it is.
Strangely enough, my "fresh" stock suspension felt so much better than my old original shocks.

[Topdownman]

I've always stuck to MT90. Yes it's 35 quid but how often do you replace it? And the difference is quite noticeable if you've never replaced it so it justifies it in your head

As far as fluids go, I just go for the best. Saving 20 quid on something I replace maybe once or twice a year in case of engine oil, why scrimp?

Ah that's good to hear it will make the difference! I've heard Redline oil is that stuff to go for.

How much oil does the Roadsters gearbox take?

All from memory, is it 1.7 litres? I am pretty sure I bought 2 bottles of the mt90. I think the mt90 is popular because it can make the gear change a bit slicker.

[1979scotte]

@Ardent

Although I have put MT90 into my 2 and would do again I agree with Jason's sentiment.
After thousands of miles changing it for anything of the correct spec will make a positive difference.

[Joesson]

Slightly off gearbox topic, but to do with lubrication and in the same general area, I mentioned a while ago about a slight leak from the drive shaft boot and consequently " "drained" what was once grease from the inner and outer bearings/ boots and replace with grease.
No noticeable difference but I felt better after seeing what came out and what I put back in.
Psychology, rather than physics perhaps plays a part in our perceptions of change.

[ChrisGB]

I've swapped one fresh gear oil for another in a stock MR2 box. 28,000 miles on stock gear oil, I was not too happy with shift quality, so filled with Silktran 75W90. This was a bit too slippery, changes where very notchy and obstructive. Drained and filled with Redline MT90 which proved to have the best shift quality of the 3. When I went turbo, it was suggested that although MT90 gives good shift quality, it may not be the best for high stress applications, so went to a Shell product, not sure which one. Good shift quality, but not quite as slick as MT90.

[Ardent]

MR2Adam

Given that Chris is arguably running the most power on here, if MT90 works for him, it will work for you.

I am running half or less juice than Chris. MPM is more than smooth enough for me.

[tow]

I am using Castrol Syntrans Multivehicle 75W/90. MT90 isn't available in my area, and the Castrol has always done good on my transmissions. Had one that had hard gearing, that got a lot better after changing to Syntrans.

[puma2]

  i have used mt90 twice now just  my go to from other people advice on here and from the who  does the work  

[Carolyn]

I am using Castrol Syntrans Multivehicle 75W/90. MT90 isn't available in my area, and the Castrol has always done good on my transmissions. Had one that had hard gearing, that got a lot better after changing to Syntrans.

I buy it from Fleabay

[J88TEO]

I buy it from Fleabay

Same here.

[MarkB1]

Millers TRX 75w-90.....it was actually the semi synthetic version but seems to work well, gear change is great. I'm not doing big miles or hard driving.