Lower Viscosity Oil and More Power?

I know the topic of oil has been discussed to death, but I still could not find an answer to my question. On my last oil change several hundred miles ago I put in motorcycle specific synthetic 5w-40. My mpg's are up slightly and the butt dyno thinks there is slightly better acceleration. Plus I have easier shifts (like downshifting from 2nd to 1st). Is this lower viscosity oil going to cause any problems in the DR? I don't seem to be burning any. My thoughts are that when Suzuki first designed this motor, this oil didn't exist, so the factory recommended 10w-40 might not be that critical. Any thoughts??

I assume that you are using Shell Rotella T Synthetic or some other diesel oil as they are about the only 5w-40 oils out there.

This quote comes from a very informative internet article titled "All about Oil' "The synthetic diesel oils are 5w-40 oils. Some people have expressed concern to me that this doesn't match the 10w-40 specification for their engine. The 5w rating only applies when the oil is cold, below about 80° f. Once your oil and engine are up to operating temperature, these are 40 weight oils, just like all the others. In cold conditions, under 40° f, the 5w oils are much better for your engine than a 10w oil."

Google the article if you want. It's a good read. http://www.calsci.com/motorcycleinfo/Oils1.html

Edited by oldmanron
attaching link

Actually, it's Castrol "Power Plus Racing RT4", specifically for bikes. I use the Rotella in my Ford F250 Powerstroke:thumbsup:

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