Hello Guy's..please bear with me,I'm new to this. I recently bought an x-reg astravan.I've noticed oil in the header tank. The van runs fine,and it does not use or lose any water. also noticed the oil level goes up and down like a yo-yo but settles where it should when dipped a couple of times.I've been told it could be the oil cooler.Now,and dont all laugh at once,I can't find where it is located.I assumed it would be at the front,possibly attached to the radiator.I can only see the intercooler in that location.I was told it may be possible to bypass the oil cooler.If this is the case,could someone please tell me where on the engine it is situated.Yesterday,I drove to Hull and back to Bolton Lancs without any problem.But for peace of mind I need to resolve this issue.Help would be much appreciated. Thank You...sorry forgot to mention..its a 1-7 dti