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Gearbox oil?

Gents, I read somewhere what oil is best to use in a gearbox, but I cant find it.

My box is the three speed type, what is the best oil to use? Straight 30?

Re: Gearbox oil?

I am no expert, but for my Chummy, the Castrol lubrication chart says Castrol XXL 40 for the box. When I got the car, the previous owner was using castrol XL 30 for the box (and engine) and it sounded as if there was a bag of loose nails in there. Changing to XXL 40 eliminated most of the racket.

My handbook (Publication 352P) says to use the same oil as the engine, so according to that I should be using XL 30, but I'm sticking to what I'm doing now.

That no doubt leaves you no wiser, but I'm sure the real experts will respond.

Re: Re: Gearbox oil?

Dont worry I currently have cheap as chips 20/50 with detergent in it, mainly because thats what I had to hand when I changed gearbox in a rush 3 years ago. (Cheap oil as the then engine burnt it so quick) it seemed to work ok, but I'm told is not the done thing with a 7 gearbox. Since I need to get some oil for the rebuilt engine about to go in, I thought I may as well get some correct stuff for the gearbox at the same time.

Re: Re: Re: Gearbox oil?

Hedd

I use cheap 20/50 in the engine and I have no problem with this.
BUT I dont use multigrade detergant oil in the gearbox. Like the back axle we have to be carefull that the additives in the oil dont eat the bronze bushes! Because of this I use GL4 spec NON Hypoid EP140 which is the correct oil for a spiral bevel gear in the back axle. You should NOT use the motor factors stuff as it is usually to GL5 spec for hypoid axles which contains additives to cope with the increased sliding motion encountered in a hypoid type axle, and will eat bronze bushes!
I use straight 30 grade lawnmower oil for the gearbox, but I am toying with the idea of using 40 grade to quieten it down a bit!

Regards

Steve

Re: Re: Re: Re: Gearbox oil?

Hi Hedd. it's a false economy to use cheap or wrong oil when you consider the time, difficulty & cost of repairing your gearbox or differential. And I'd put up with some noise rather than rebuild either, which I've had to do in the past because of these oils that contain sulphur and a lot of other nasties for pure bronze bushings. (Modern alloy-bronze bushings aren't harmed by these). If you use your car daily & replace all the oil very often you might get away with it, but then you haven't saved any time or money have you? If car is left standing for long periods with modern detergents oils therein, I'll guarantee the A7 bushings will be affected. Austin recommends engine oil, but of course oils have changed since Sevens were produced. On NO account use any modern dertergent oils in box or diff. Look for oils made by firms producing oil especially for old cars. One I know available in UK is Penrite - Gear oil 30 for box, Trans oil 140 for diff Many companies make agricultural oils, some of which are okay, but Check! No doubt you'll come across people who claim they've had no trouble with M.D. oils, but give them time. Many years ago I wrote a paper on this subject (in fairness the idea was instigated by a question from a Kiwi A7 friend) which was incidental to my A7 diff collapsing at the same time. All oil companies interviewd except one (and that was unofficially)denied there was a problem. This paper was published gradually around the world with most initially poo-pooing the idea, but finally sanity prevailed. I think Penrite were the first to agree with my argument & produced a range of oils to suit old cars. You'll even get oil companies admitting the problem nowadays. Cheers, Bill in Oz

Re: Re: Re: Re: Re: Gearbox oil?

so in amongst the why and what for's it seems straight 30 is the stuff to use. Question answered. Many thanks