Oil burning smell coming in vernts

Hey fellas, and fellet's. I love my little car. It's been having this burning smell. It does it every so often. It's like a hot oil burning smell. Stink's pretty bad. I would like to know if anyone has had th same problem. Or if there are some thing's I can check out.

Spec's;

2004 5 speed with 165 000km on it. I have replaced the time belt. And the valve cover gasket has been done. I did switch back from synthetic to regular oil.

Thank you in advance for all help. I paid $2600 for her 6 years ago. Had 95 000kmon it. And it was yellow. I painted it with a roller. haha. I lover her though. She ain't pretty but I take care of her.

-Mike

If you've done the valve cover gasket, my guess would be either crankshaft or camshaft seal. Which sucks because it means getting in under the timing belt setup. My 2004's crankshaft seal was seeping a bit. Every once in a while it would drip on the exhaust and you'd catch a burnt oil smell in the car.