Oil Viscosity

[Goshawk]

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?

 

[glider]

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.

 

[Electraglidin']

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