oil seal 1600cc

no rear seal on a "stock" 1600 for the Beetles for the crank pulley only a couple of front seals for the flywheel

If you have oil coming out then the internal pressure is causing blowby. Is this a fuel injected engine?

Uh, yes it is a F.I. Engine I should say. Quite fascinating. Does this particular engine usually have a lot of internal pressure?

When you say harmonic balancer, do you mean the flywheel?

Sometimes there is a 'sand seal' on the crank pulley end.

This site could be of some help:

Fascinating that it is fuel injected? Or that I took a wild guess and asked a logical question? lol Some people block off some hoses to the FI-ed engines and that creates too much internal pressure and forces it out of the crank pulley. I have seen this where 12 quarts are blown out in less than 300 miles. UGLY. Make sure all of those hoses to the manifold are not blocked off and are correctly attached. After you correct it you can drive from Chicago to Alaska at 80 mph and only use maybe 2 quarts.

Or it could be something else like a bad piston causing the internal pressure. :-(