Prices....Rant...World Gone Mad. Motorcycle Oil

I still say 15w anything is too thick, and 5w anything is too thin, so diesel oils are out. They make 10w40 in rotella, but you can't buy it unless you like $16.00 a gallon plus $20.00 shipping ripoff. I've used Valvoline 10w40 motorcycle oil from Walmart for $3.94 a quart and it works fine, but not the high zinc content apparently. Castrol Actevo at Walmart at $5.50 or so works fine. Valvoline full synthetic is now around $6.50 a quart at Walmart. I hate to buy at Walmart like anyone, but same oil I buy a gallon of at Walmart is $15.00 a gallon, and at Autozone $24.00.

The W number rating is for "winter" (cold) flowability. The lower the better because that means the oil pumps easily at cold startup temps where the oil thickens up. 15W (or 20W) is going the wrong way compared to 10W, but it's fine as long as you don't take your bike out in the dead of winter when it's below freezing. If you do, I'd go to that 5W stuff.

Once the engine warms up the W rating in the oil is not applicable anymore. That's why there are two different viscosity ratings; one for cold (W number) and the other for normal running fully warmed up.