Originally Posted by Gummikuh
To be honest i wouldn't use higher grade stuff. These Engines and the Gearbox are developed during the '60-'70 They are not made for all that new stuff.
True - GL4, splash lubrication.
I've used Omega GL7 sticky-climbing-glueish super EP since about 1996. Smoother, much more quite, no metal shreeking when pulling out from gas-stops - tested this now for about 200 000km. There is no way I'll run any other kind of oil less I fail to get hold of Omega 690 80W/90.
What happened back in 1997 may explain why I am so determined on this aspect, as well as the broken final drive this summer.
Do this very simpel test:
Take a any kind of mechanical whisk from the kitchen assessoirs (I used a hand-powered) - spinn the whisk in the hypoid and look what happens. Then compare that with whisking Omega 690. When you do that, and see with your own eyes, and feel the difference in the whisks mechanical motions - then you know why I say what I do.
Most important question though: what happens to the large bearing?
Sorry, not even Omega 690 can stop it from failing at about 100 000km -
What sticks in your mind is however the even older than 1981-on gearboxes, older than the /7,... - those that have brass components; those that will be damaged by from GL4 and up. GL4 and up "attacks" brass.
All /7 can use the highest GL -