I have a 2002 Toyota Solara with 195k miles, and it frequently gives off a hot oil smell as though oil or trans fluid is on a hot surface, but I cannot find any such thing through a visual inspection. About the time this started, the check engine light came on and stayed on until I replaced the upstream O2 sensor.
I had hoped there was some connection, but the sporadic smell has continued, so apparently not. Is there some other explanation, or should I keep looking for a leak somewhere on the outside of the engine?
There might be a little oil dripping out of the valve cover gasket onto the exhaust. It only takes a few drops to cause a significant bad smell. You need to take a better look at where oil can get on the exhaust.
This V6 is known for valve cover leaks, that’s what happened to mine. If you do go to the expense of replacing both, have the spark plugs replaced at the same time. Just make sure they don’t double charge you for the intake manifold removal.
I believe that Docnick is on the right track.
Even though the OP has done a visual inspection, the reality is that the rear bank of cylinders on that V-6 is not readily visible. If the OP can get up close with a strong light, he will likely find that the valve cover gasket for the rear bank of cylinders is seeping oil onto its exhaust manifold.