I'm apt to do a considerable amount of Winter riding. Usually if the temps aren't below 17 degrees or so and it's going to be a pretty day, I can usually find an excuse to take the bike to work. It's almost an hour's commute, so it warms up well and condensation shouldn't be a concern. Average Winter (Dec-Feb) temperatures in Middle Tennessee are fairly moderate, with 30 being the average low and 49 being the average high, but I'm more concerned with operating the bike on those 17-25 degree days. Those are the days that seem to always be nothing but clear blue skies, and ideal for a pleasant ride... I picked up a shop manual the day I got the bike (my choice of a free gift for the purchase), and it states that below 40 degrees a 10W40 weight is recommended, but I notice that the weights change in 20 degree increments. So my concern is should I possibly go to a synthetic 10W30 maybe in January or leave the 10W40 as it is? Possibly a different brand of 10W40 synthetic that will "flow" better at below 20 degrees, as it's not uncommon to have a 17 degree morning and 30 degree afternoon ride? Also the manual is calling for standard HD lube in the primary and transmission across the board, with no temperature variations. Is this the general consensus for below 20 degrees? Last Winter I used HD 10W40 and gave the motor a good 5+ minutes of warm-up (the amount of time to suit up) before setting out and never had any issues, but was always worried about doing some damage to the internals, especially so at higher speeds of 60-70 mph or so and the engine at it's peak cooling efficiency. Sorry for the long drawn out post, I did a search and didn't find what I was looking for, just wondering what some of the forum more familiar with this motor have done in the past... On the water cooled metrics it's fairly easy to just cover a portion of the radiator and go, not so with an air cooled motor, and I want to make sure I approach this right.