What is the best synthetic oil for the M109
Motorcycle Oil Technical Facts
Lamonster Oil Change
What oil do you use?
Engine Oil Difference
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:agree: Stick with 10W-40. Your current Amsoil or Mobil 1 4T are both excellent choices. I would not do 10W-30 in your area. Your average summer high exceeds the Suzuki max for 10W-30.I would stick with 10w40.......