MGB Gearbox oil

[edvaldez]

As the title suggests really, my gearbox is a little whiney and I haven't a clue when or even if the gearbox oil has been changed in its life. It is a '72 non O/D 4 synchro and i have read many things some suggest 20w/50 engine oil some suggest redline mtl some say a regular gl4 mt90 so anyone with any experiences can you suggest anything?

[adam73bgt]

20/50 engine oil is what the original manual recommends and is what I've used for a couple years now without issues I've never used any specific brand, just used whatever was going in the engine at the time lol

[ChasR]

AFAIK only the OD cars need engine oil. 20W50 to be exact.

In yours EP90 will be just fine.

[edvaldez]

Thanks guys, ChasR that is what I read a few times but I would rather trust some of you guys who actually drive their cars over most of the owners club lot who drive them once a year.

Has anyone used any of the redline MT90 or MTL? or is it not worth the extra pennies?

[adam73bgt]

Jan 30, 2015 20:29:43 GMT ChasR said:

AFAIK only the OD cars need engine oil. 20W50 to be exact.

In yours EP90 will be just fine.

I must admit I hadn't looked at whether there was a difference in oil between the over drive and non over drive cars

Though I'd imagine it wouldn't do any harm to use 20w50 in a non overdrive gearbox?

[Deleted]

On the basis that they have the same box as Triumph EP90 should be used, I have never known or heard of anyone suggesting putting 20/50 in a gearbox and avoid any oil that contains sulphur as it will eat the brass seals.

[adam73bgt]

Jan 31, 2015 1:42:12 GMT @1300dolly said:

On the basis that they have the same box as Triumph EP90 should be used, I have never known or heard of anyone suggesting putting 20/50 in a gearbox and avoid any oil that contains sulphur as it will eat the brass seals.

I'm pretty sure it was only the Midget that used the same box as Triumph? The MGB box is different as far as I know

Well this is what the manual states, as I say 20w/50 has worked fine for me

[Deleted]

okay, I stand corrected.

[Seth]

Engine oil is frequently used in gearboxes, certainly all pre BL 'B series' gearboxes. The later Marina box (which was derived from a Triumph box and differs from the MG one) is specified with EP90 though. Looking at my Rootes manuals engine oil is also used in all the medium sized cars from '50s on.

With overdrive cars I think you have to be very careful about using any sort of friction reducing additive though.

[ChasR]

Jan 31, 2015 18:58:50 GMT Seth said:

Engine oil is frequently used in gearboxes, certainly all pre BL 'B series' gearboxes. The later Marina box (which was derived from a Triumph box and differs from the MG one) is specified with EP90 though. Looking at my Rootes manuals engine oil is also used in all the medium sized cars from '50s on.

With overdrive cars I think you have to be very careful about using any sort of friction reducing additive though.

With the latter that is how I understood it as well.

I am sure with a previous manual I owned it specified EP90 for non O/D boxes. Whilst there is probably not much harm in using 20W50 it is probably best to use EP80, which has more additives in to suit the punishment oil takes in gearboxes, now that the reason for using engine oil (the OD) has now gone.