batman
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SuzukiSavage.com Rocks!
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osceola new york
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The numbers on oil cans be misleading, 15w40 (dino) means that the oil is based on 40 weight and has an additive package that brings it down to15 weight at operating temp. It is improper to think that oil gets thicker when heated ,as the truth is it gets thicker as it cools.the viscosity of 15w40 at 75 degrees F is approx. 150, and doesn't lube well,that is why 90% of wear occurs when starting a cold motor,and why you should never rev the motor to warm it faster .As this oil ages the additive package wears out and the viscosity drops(past oil change time),if left even longer waxes form in the oil and viscosity raises and fails to lube properly. 15w40 synthetic ,on the other hand is based on 15 weight 'oil' and the viscosity a 75 degrees is about 40 ,so it also fails to lube at starting but comes to operating temp sooner causing less wear,the viscosity of this oil will not drop past 15 but if not changed will also thicken. the use of 20w50 oil causes oil pressure to be higher,but motors are lubed by the flow of oil through the motor., the more pressure the less flow (minimum pressure is needed to pump the oil through the motor ,but heavier oil drives the pressure up causing higher resistance to flow in the oil passages ,slowing flow and makes the motor run hotter.)So the use of heavier oil into warmer weather is counter productive! AS Vercy stated above he tried 20w50 in the heat and found his motor ran hotter.
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