No smoke, but oily residue on trunk

[ncarrick783]

I've got 2000 Protege LX 1.6L with basically no aftermarket parts. In the past year it's started burning oil pretty fast, and I've noticed there is a black, oily buildup that accumulates on the rear bumper and rear trunk panel after a few days of driving. There's no visible smoke from the tailpipe that I've ever seen or smelled, but that's kind of what the buildup looks like. It's spread pretty evenly across the whole back, but might be a little heavier on the tailpipe side.

Some of the oil loss will hopefully be stopped after changing the valve cover gasket earlier today (which was leaking more than a little), but there's clearly something going on with the exhaust too. Any ideas what I should be looking for?

 

[mazdadude]

Once the oil control rings on the pistons freeze up, there is very little you can do about the oil burning without replacing the rings.

Here is a pic of a Mazda piston with the oil rings stuck on the left, and what they SHOULD look like in the right... (bottom ring group is the oil control rings)

 

[ncarrick783]

Thanks. I've read that using a higher viscosity oil might help some. I'll probably try that, and a new PCV valve.