burning oil
I am out of ideas. If the oils clean, like its been changed not so long ago, top it right up to the top and drive it for awhile--if you can, with these cell phones it does not take long for a cop to find you if you piss everybody off.
I say just drive it because maybe it get better, or worst. Thats how I found my bad head gasket, I thought it was the valve seals cause it smoke very bad starting up but then seemed OK for like a day. Next day the gasket blew right out, I guess I was lucky the piston did not lock up with so much oil inside the hole.
So maybe driving it is not a great idea.