Originally Posted by oyster_gold
I did notice a bit of white smoke from the exhaust when I returned from a little test drive around the block. Also, it could be my imagination but it sounds like the engine is louder (engine sound from bay, not from exhaust). When I bought this car last year the dealer had changed the oil (obviously not the air filters!!!) and the sticker they put in the windshield said 'Penzoil - 5W-30'. I've done two oil changes since then with Mobil 1 0W-40. Does the thinner oil allow more lifter, cam, crank "noise"? Engine runs great and I've never had any issue with this car since I've had it.
Synthetic oil generally doesn't offer quite as much niose surpression as a petroleum base oil does. If the dealer put a 5w-30 Penzoil sticker on the car it still could have been synthetic oil. But if you started hearing more mechanical noise after a couple of Mobil 1 oil changes, maybe the dealer did infact use straight petroleum base oil when they changed it.