Just bought a Del Sol with a D16y7 (around 80k miles). Apparently it leaks/eats oil at a very quick rate. It was running fine untill I started it this morning. I filled it with oil then started it; it was missing, had no hp, kept trying to stall, and was billowing white smoke. The smoke smelled mostly of gas, some oil, but no antifreeze. The intake sounded louder than usual. Lots of oil on back of engine, but I can't tell where it's from.

What is it and how can I check?

 

Compression test the cylinders. See Forty04's DIY.

 

Hello,
Like ronj said do a compression check. You have a problem with the oil use. You could have bad rings or a bad head gasket. Please keep us posted and I hope you solve the problem. Thanks, 2010civiclx

 

White smoke and missing, it sounds like a bad head gasket.
If you are smelling gas at the back, you would see black smoke.

Oil smoke is white with possible blue tint.
Steam is white.
Too rich burn is black smoke.

Look for bubbles in radiator while engine is running.

Oil leak in the back of engine may be from leaky oil pressure switch, loose oil filter installation or leaky head gasket. I think oil supply galley is at the back of block.

 

Sounds like a blown head gasket to me.