Fuchs 10W/50 for me. I woulden't use anything less than a fully syn 50 weight.

Nothing wrong with Mobil either as it's liked by others.

Don't use 5W/30, it's too thin for these or any old engines, it's not so much that it will leak but it won't protect the engine properly, and it may burn it, remember these engines don't have the close tolerances of modern engines!

Martin