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Oil Viscosity


It seems most people run 20/50 engine oil yet the manual says if the temperature
falls below 40 degrees before the next oil change to use 10/40. Why is this ignored?
The main reason for the lighter oil is for starting in the cold temps. Once the engine is running and warmed up, it makes very little difference between the two.
I think the reason most folks don't bother is that many don't ride when it gets below 40 deg F.
I was changing from synthetic 20W-50 in summer to 15W-50 synthetic for winter because I ride my bike down to about 25 deg F or so, & I figured I'd get a little better cold weather startup protection. Talked to the service guru at my dealership & he said when running synthetic 20W-50 it really wasn't necessary to change viscosity till the temps got to around 10-15 deg F. Makes sense, since synthetics offer better flow characteristics at low temps than dino oils...

It certainly wouldn't hurt to change to 10W-40 but for me, in the temps I ride in, I'll stick with 20W-50 year round. :s