MY 2002 supercrew FX4 seems to be using about a guart of oil every thousand miles. It has around 96000 miles and I have been using synthetic since I bought it with 38000. I use Mobil 1 5w20 as that is the weight called for. Is this stuff so thin that it's getting by the rings and/or valves? It is definitely not leaking out anywhere. Any thoughts would be appreciated.

 

try a new PVC valve.

 

maybe thats PCV. if the valve sticks, then you get excess vacuum on the crankcase and it will suck oil and burn.

 

Thanks for the idea. I'll check the pcv tomorrow.