I work at a commercial power equipment store and today a customer came in with a Kawasaki 17 hp. V twin on a commercial mower.The unit had over 1300 hrs. on it and ran like a top, no oil burning no death rattles , ran better than some new units.So he says to me "runs good huh?" Well it turns out that he has been running Mobil 1 10w30 since day one. Now a little side note, this motor usually never sees this many hours with out major engine work so it seems that the use of a good synthetic does in fact prolong engine life. I also ran a compression check on the motor and both cylinders were within 5 psi of a new unit that was in the showroom.I guess Mobil 1 will pay off in the future.