gearbox oil 1955 ish swing arm B31

[rustyboots]

Hi all

I have just drained the gearbox oil, which seemed to be very thick indeed,

I intend to use Straight 40 non detergent in the engine, can i use the same in the gearbox ?

Haynes manual says same oil for engine, gearbox and primary, allthough it does not state sae 40,

I have chosen this oil after looking at various forums and who uses what and why,
so many different answers and views, even arguments on this oil subject.

How ever I do need a bit of help please.

Mark

[idie]

It should be sae 50.

[rustyboots]

It should be sae 50.

Is that for Engine or gearbox ?

[DAVE BRADY]

Hi,

In the gearbox use a proper gear oil.  They are available for classic boxes that use bronze type bushes. The gear oils are formulated to cope with the pressures of the rotating, chopping action of the gears.
In the primary case many people now use an auto transmission fluid. The ATF keeps the chain lubricated but is far less likely to cause any problems with the cutch plates slipping or sticking.
I have used ATF in several bikes over many thousands of miles from a hard working A10 combo. to a very high mileage A10 and A65.

Dave.

[rhyatt]

Be careful of GL5 gear oils.
Gl5 can be detrimental to bronze bushes.
Use gl4 or whatever the manual says

[rustyboots]

Be careful of GL5 gear oils.
Gl5 can be detrimental to bronze bushes.
Use gl4 or whatever the manual says

The Haynes manual says engine oil everywhere

So many different answers to one question, don't half get confusing🤔

[neil1964]

I use the same GL4 in my BSAs in my MGB and Landrover's gearboxes, diff. and transfer boxes 

I use 85/90 and have done so for some time.  I should really buy it in 20 gall. drums!

[JulianS]

I use Morris AG90, safe with bronze bushes.

https://www.morrislubricantsonline.co.uk/golden-film-ag-90-gear-oil.html