Weird smell!
 

I replaced my leaking crank seal in December along with both of the belts. I also switched over to Mobil1 Extended Performance 5-30. My car has 122,XXX on it now and ever since I did all that work, When I get on it or floor it there seems to be a burning smell. There arent any leaks that I know. The only think I can think is something leaking on the exhaust but like I said...No leaks that I know of. I can smell it with the windows down or up. Any ideas!?!?

Could be a little residual oil on the exhaust manifold that is laying there waiting for you to "get on it" and heat up the exhaust. Could be a little spilled antifreeze doing the same thing. Could be a dead animal.
You're going to have to get in there and look around real carefully.