I have been using Mobil 1 10-30 (tri-syn I think) and I need to change the oil for the year. Are automotive oils better than the small engine oils by the various manuf or the HD 30 Pennzoil? It doesn't seem to use any oil and I have about 35 hours on this oil and about 50 hours on the engine. If I remember right the manual calls for straight 30 but allows 10w30. I would like to get many more years out of this mower.