My manual says to use either 10W30 or 10W40 oil in my 2006 Yamaha F200. Which one is better to use in SC and why?
“The problem with socialism is that eventually you run out of other peoples money”
GW 205
F200 Yam
10W30 in the winter and 10W40 in the summer…10W30 will “flow” quicker in cold weather and 10W40 will protect better in hot weather. there is chart most of the time that says 10 deg to 85 deg use 10W30… and 30 deg to 100 deg use 10W40 give or take a deg or two
I like your avator… mines bigger though 
26’ Twinvee
Suzuki 175’s
www.creeksidemetalworks.com
The w stands for winter. Or winter weight as some call it. Neither oil will flow quicker when its cold because they are both a viscosity of 10Winter. The 40 will not “thin out” as much when it warms up. Viscosity is not the actual thickness of the oil but the rate that oil will flow. Obviously thicker oil will result in more pressure however less flow because its easier to flow a thinner fluid. I agree with capt ed somewhat on his logic. However its best to pick a weight and stick with it. It really doesnt get cold enough here to make a diff. The engine is going to heat the oil up to the same operating temp in the summer as it does in the winter. Theres an oil cooler on your engine im sure. And thermostats that maintain the correct water temp and water is what cools the oil through the cooler.
Thanks RS and Chris V. I’ll go with the 10W30 all around.
Captain Ed, yours looks a little thicker but mine is longer. You brought a sausage to a weenie roast.
“The problem with socialism is that eventually you run out of other peoples money”
GW 205
F200 Yam