Winter Oil Viscosity in snowbelt

[Coldfinger]

That chart is in my owner's manual.  I note that 15W40 is listed as an acceptable viscosity.  The only oil I have ever seen in the 15W40 viscosity is also rated CC/CD for diesels.  My manual specifically says not to use any oil with the C rating.  Kind of weird since Shell Rotella also carries the motorcycle rating JASO MA.  I always used Rotella T in my Honda but this is a different bike with a lot more power.  I guess I will use Mobil 1 V Twin oil...with 10W40 in the cold season (fall and spring) and 20W50 in the summer.  I ride about 12,000 miles/year so 3 oil changes.
[/quote]

I was poking around a little and my owners manual says not to use CD rated oil.  The CD is obsolete.  The Rotella 15w40 is not rated CD.

From the website:
http://www.oilspecifications.org/api_eolcs.php
CD
Obsolete

Service typical of certain naturally aspirated, turbocharged or supercharged diesel engines where highly effective control of wear and deposits is vital, or when using fuels with a wide quality range (including high-sulfur fuels). Oils designed for this service were introduced in 1955 and provide protection from high temperature deposits and bearing corrosion in these diesel engines.

[bigjohn]

the laws of oil viscosity in relationship to temperature do not fail to exist because the sticker on a raider motor says 'yamaha'...or at least i can't see how...the actual running temperature of the oil on a cold day would point to what viscosity to use.........and i'm to cheap/lazy to install a guage i'll probably just run the 10-40....although one night last january it was 15 degrees out and that 1900 sounded a little funky starting up and i really wondered about the oil too...big john

[GlacierBlue]

the laws of oil viscosity in relationship to temperature do not fail to exist because the sticker on a raider motor says 'yamaha'...or at least i can't see how...the actual running temperature of the oil on a cold day would point to what viscosity to use.........and i'm to cheap/lazy to install a guage i'll probably just run the 10-40....although one night last january it was 15 degrees out and that 1900 sounded a little funky starting up and i really wondered about the oil too...big john

Hmmm...I thought the reason for different viscosity in cold weather was so it would flow when the engine is first started.  Once the engine is warmed up, what difference does it make?  Stated another way, if my Raider had 20W50 and I started it in a 60 degree garage, and then drove it continuously in 20 degree weather, I wouldn't think there would be an issue, would there?

[Coldfinger]

I'm looking for easier cranking for those times when the bike sits outside all day and it's 30 degrees. 

As far as 40 or 50, I think 40 would suffice for every month for my use except I prefer a 50 in July and August.

Now thinking about that, maybe Mobil 1 10w40 would be the best choice to use year-round.  I wonder if there is any difference other than viscosity between their 10w40 motorcycle and 20w50v-twin oil.  Maybe I'll call them and ask unless someone here knows.