MORE Oil Discussion - Impact on Fuel Economy

I swear that the weight of the oil is playing a significant roll in my fuel economy - by significant, I mean enough that I actually notice.

It appears that 10W40 gave me better fuel economy than the 15W50 ... but my bike shifts smoother and quieter on the 15W50.

The next oil change, I'm going to try going in the other direction and try the Rotella 5W40 to see what happens.

Anyone else experience this?

 

05-40 Castrol rt -m2 rating the very best, is better and should be best for fuel mpg, rottella is has only a ma rating

 

It makes a kind of sense since the higher viscosity oil should take a bit more power to move through the engine. But I really can't see it making a noticeable difference in fuel usage. JMO of course.

 

Yes, oil weight makes a big difference. Many new cars require 0/20 in order to meet emission standards. California takes it so seriously that they actually go to oil change shops to test the oil in the 0/20 tanks and make sure they are using 0/20 where called for.

 

The 5W40 Rotella will be a little thinner at startup but at operating temp should be exactly the same as the 10W40.

 

Maybe since the higher viscosity lubricants weigh more, it takes more fuel to move the bike. Porking oot may be adding or subtracting to fuel usage too. Less crunching munchies or crunching hard numbers might evidence this phenomena.

Too oily to tell at this point.

 

I got around 45 MPG on a all highway trip. My speed was constantly between 70-85 for the most part. In my city riding conditions I usually get 35-37mpg since most of my riding is for less than 5 miles one way with 7-8 stop signs/traffic lights. I'm running rotella 5W-40.