Porsche Enthusiasts Club Forum

Is there a seperate oil resevoir for the rear differential, or is it part of the automatic transmission?

If there is, how do I check the level?

It's separate from auto.

You can't check level as it's assumed the oil isn't going anywhere, but you can change it.

Remove upper fill plug and lower drain plug. Turn wheel to help expel oil.

Takes 3L of gear oil

Hi

Good advice....one more thing.....make SURE both the upper and lower plugs are free as if the upper is locked solid, you will drain out the fluid and NOT be able to refill lol

All the best Brett

Don't you fill it to the level of the upper plug (filler plug) then, like other cars I've owned?

Hi

Yes you fill it until it JUST overflows....

The point I was making is that you cannot fill it at all if the upper plug is seized into the casing.....so make sure it isn't BEFORE you undo the bottom drain plug and drain it...

All the best Brett

The diff oil plugs are notoriously tight.

You can reduce risk of stripping by using penetrating oil first, and thoroughly cleaning the allen heads so that the key or allen socket can go as deep as possible into plug.

You need two new seal washers - I think they are same as the one for engine oil.

Thanks for the advice. I think I'll just take the top plug out (if it will come out) and check the level. I know it's not going to be the case on the 928, but on the last car I owned (a 1932 Standard Little Nine saloon) when I checked the level there was nothing in it at all. The differential survived. Mind you, it only had 23bhp to contend with....10mph max on some hills round here.