Best gearbox oil for an aircooled ? I'm wondering about the GL4 v GL5 argument - and which brand that is available in the UK Which do we recommend ? Thanks Al
If it leaks...use supermarket equivalent....if it doesn't, use Morris straight 30, hell anything is better than not changing it :
it should be gl4 ep80 or ep90 but ive used gl5 ep80/90 for ever no probs but if you are desperate to use gl4 millers do a classic ep gear oil that is suitable
17mm allen key at side of driveshaft for fill and level and 17mm allen key underneath the gearbox at the front edge to drain. top tip make sure the filler plug will undo before removing the drain plug or you might be stuck with no oil in the box!!!
if you plan to do this with the box in-situ you need a big drain tray, and need to smear your upper body in goose fat. Makes it easier to get the stinky oil off when you get covered in it Warm the oil up first too with a run around the block.
I have an oil pump with integral container full of Millers synthetic that does all of my gearboxes / final drives.
I used Castrol Synthtrans 75-90w GL4 rated. It's expensive at about a tenner a litre but its fully synthetic. Found some website doing a special offer and got it for £8.50 a litre. Much better change when the engine is cold now, not so stiff.
