Mobil 1 full syn at $105 per case of 4/1gals. Truck takes 2 1/2 gals. Which syn are you buying?YZ250B;1590101; said:I have been a beleiver in synthetic oil for some time but now i am thinking a new routine. Tell me what you guys think. Synthethic runs $85-100 every oil change while penzoil runs around $65 so I can change the oil twice as much with regular oil for the same cost as one syn change. Since soot is what you really want to remove and these engines barely hit 3000 rpm does it not make sense to just use regular oil and change every 2k for the best engine porotection?