Vectra diesel oil cooler - Quinny
Following my recent post regarding my alleged head gasket failure on my 97 Vectra diesel,I've had it checked out at the local diesel centre,and he is of the opinion that oil coolers on these cars tend to fail,more than the head gaskets.

So he's flushed the system out,as the header tank seemed to contain more oil than water,and he's by-passed the oil cooler.

Now,does the oil cooler have water flowing around it somewhere to keep it cool,because until I see what he's done tomorrow,I'd like to know what's been by-passed,if not,what has he by-passed?

What he has said as well,is that the system may need flushing a couple of more times to try and rid it of any remaining oil in the water,so if that is the case,in order to help it,are there any products on the market that I can add,to dissolve any remaining oil,before it has it's final refill with anti-freeze?

Failing all of the above,it looks like a new oil cooler is on the cards,which is the route I may go down anyway,as I'm not a big fan of by-passing a system.
Vectra diesel oil cooler - rebel
Your Vectra does have an oil to water intercooler and these do sometimes leak internally.
Bypassing it will do no harm in the short term as long as you don't work the engine hard for any distance, but obviously if it is leaking it should be replaced.
I have flushed heavily oil contaminated cooling systems with a strong Jizer mixture to very good effect.