Now that they replaced my motor, how do I keep the car from coking the valves? I did do the valve cleaning on the old motor but after 90k miles they were terrible. I have a a 2.4 theta ii motor, i do have an OCC installed with a inline water/oil air seperator for a diesel routed to intake side, I do catch oil in there and the nasty additives but I was wondering as to what can prevent this as it only has 200 miles on it now.