> 
> My Transporter, a 1991 1.9L diesel T4 (as no doubt you all 
> it's not.  I like driving in circles!)
> 
> I have two questions.
> 
> 1.  What is 'blow-by'?  Something Porsche 911s do on the 
> outside lane? :)

Ahhh...My favorite topic :-(

Blowby in diesels happens because the compression ratio of diesels
is about 3x that of gas-burners (You gotta real squeeze it to burn it)

So, as the rings wear, "stuff" {actual technical term) blows-by the
rings and pistons into the interior if the engine. This stuff is
unburnt diesel fuel and air. The air puts internal pressure in the
crankcase which does Uri Geller-like stunts like loosens oil-fill cap
magically.

As previously mentioned, blows out valve cover gaskets, seals, and also
lets diesel fuel into the oil diluting it. 

You have another 100K before you really have to worry.

Matthew
drahzal@convex.com