96 Ford Explorer XLT 4.0 V6 2WD 4DR Auto Trans
148k miles
Noticed every once in awhile a smell of, what i think, is oil on the exhaust manifold burning. The truck DOES NOT leave an oil leak, or any kind of leak, on the driveway or where ever it is parked. Had shop tighten down valve covers, since this is the only place oil could leak and get on the exhaust manifold to burn.
I guess my question is could this not be an oil leak?
The shop said there would be oil on the ground somewhere if it was...HELP still smell it !!!

 

Still sounds like an oil leak.

Tightening the valve covers usually doesn't work. Probably leaking from the gaskets down onto the exhaust.

 

You can also have an internal oil leak, check your tailpipe and your plugs for signs of oil, you also forgot to mention do you use oil between changes?

 

I havent noticed any different usage in oil. A friend of mine told me to let the car sit for a few days then start it up, if a puff of smoke came out of the exhaust then there might be an internal leak, but I didn't see this when it was tried.

 

If you suspect a valve cover leak you have to replace the gasket, also sometime these tired old engines just smell that way. Check your PVC.