Morris Minor Owners Club

I’ve done 1200 miles since a gearbox oil change, that was 5 years ago. Should I change it again ?

No ................
The gearbox oil does not get contaminated with engine crud so in theory it could go on for ever.

I suppose it was a slightly sarcastic suggestion Phil, re my recent discovery of apparent lubricant lifespan !

Lubricants do have a lifespan but 5 years is nothing to worry about in a gearbox. If you have ever smelled the vile stench of ancient Armstrong damper oil you would not doubt that lubricants go off eventually!

Stephen

Does it not get slightly thicker in the gearbox over time?

WHY?

I dunno, that's why I asked the question. Just something an old-time mechanic mentioned to me years ago..........others here may know the answer.

Morris Motors, in their lubrication chart, recommend a gearbox oil change every 6000 miles. That was using Castrol XL,straight S.A.E. 30, though.

Considering that the oil is several million years old a few extra millennia is not going to hurt.
Only when contaminates are added to the oil does the need to consider changing the oil occur.

Feel free to leave the oil in there forever Phil.
I will continue to change it. I only quoted Morris Motors own recommendation. What did they know?
It may well be millions of years old but I suspect adding some crude, without refining, to the gearbox might not end well.

My quote should be taken as a 'tongue in cheek' comment and not taken too seriously.
Even after refining it is still several million years old - so could be classed as S/H.
When I worked in the BMC garage one of the mechanics had a Morris traveller, he used to drain Morris Minor gearboxes, let the oil settle and then use it in the engine of his Minor. He never had any problems with using S/H gearbox oil in the engine and he was very particular as regards the servicing of his Minor.