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Austin Ruby gearbox oil

Austin Ruby gearbox oil. Having read a number of previous items here on the forum relating to the gearbox oil on Austin Severns. I am more confused than ever as to what oil to put into my 1935 Ruby. Some people quote gear oils of around sae 90 whilst others just recommend normal engine oil of sae 30. I now having read most of the articles on oil for the gearbox and understand (I think) that gear oil sae90 and engine oil sae30 are roughly of the same viscosity. This still leaves me with the same question. Can I put in sae20/50 engine oil into my gear box without causing any damage. I understand about not over filling the gearbox and only putting 1.25 pints into a four speed synchro box. I would appreciate any replies from others that use engine oil.

Yours John Mason.

Location: Nottinghamshire

Re: Austin Ruby gearbox oil

Yes John, you can safely use SAE20W50 multigrade in your Ruby gearbox.

Ian Mc.

Location: Shropshire

Re: Austin Ruby gearbox oil

I use 20/50 oil.

Re: Austin Ruby gearbox oil

Yup. 20/50 is all I use.

Location: Autumnal Hertfordshire

Re: Austin Ruby gearbox oil

John Mason
.....gear oil sae90 and engine oil sae30 are roughly of the same viscosity.


At room temperature they don't seem similar. 90 gear oil seems thicker.

Re: Austin Ruby gearbox oil

John,

As I have mentioned - the viscosity chart shows that the viscosity range of an SAE 90 gear oil is the same as an SAE 40 or SAE 50 engine oil (not SAE 30 engine oil).

I always use straight (GL3) SAE 90 Gear Oil in the gearbox of my cars, but as pointed out, in UK that could be a bit too viscous in your cold weather.

I think that SAE 20/50 engine oil - which means SAE 20 viscosity when cold and SAE 50 visosity when hot in an engine, might be a little too light for the gearbox, plus the churning action of the gears can reduce the visciosity index improvers performance unless it is a synthetic oil.

I would use a monograde SAE 30 or 40 engine oil in the gearbox.

Tony.

Location: Malvern, Melbourne, Australia.