10w40 vs. 10w50 Heat transfer for air/oil cooled

[vortex9]

For a Bandit 1200 air and oil cooled inline 4 motor.

I was just wondering how much a 3cst difference in viscosity at operating temp would affect the oil flow rate and heat transfer.
I normally use Motul 5100 10W40 but lately traffic due to construction in summer is ridiculous here in Montreal. I am considering switching to motul 5100 10W50 for some added protection when stuck in traffic as lane splitting is illegal here. My main concern is will the benefit of added film strength be out weighed by lower heat transfer rate due to the thicker fluid? I do not have a temp gauge on my bike. The Bandit has a rather large oil cooler up front.

Thanks!

 

[Bluestream]

Stick with the 10W40: it won't let you down...

 

[beanoil]

10/40. Too much viscosity spread for me in a shared sump motor to run a 10/50. In fact, I'd go to a 15/40 HDEO in that engine and call it a day. That large oil cooler you mention will take care of the engine just fine. Your engine is a mature design that in the past has been hot-rodded for drag racing, and was in the original GSXR and Katana line. The GSXR's held their own in Superbike being air/oil cooled, wide open most of the time, and were very reliable.

 

[GMBoy]

Originally Posted By: beanoil
10/40. Too much viscosity spread for me in a shared sump motor to run a 10/50. In fact, I'd go to a 15/40 HDEO in that engine and call it a day.



THIS.

 

[sunruh]

Originally Posted By: beanoil
10/40. Too much viscosity spread for me in a shared sump motor to run a 10/50. In fact, I'd go to a 15/40 HDEO in that engine and call it a day.


i didnt want to quote the entire perfectly spelled out post, but when you're dead on right you are RIGHT!!!

+1000 on this info.

steve

 

[dparm]

10w50 probably isn't necessary. That grade is targeted at Ducati owners, methinks.

 

[Robenstein]

Originally Posted By: dparm
10w50 probably isn't necessary. That grade is targeted at Ducati owners, methinks.


And us Triumph owners now they went from 15w50 to 10w50.

Good advice on sticking with the 15w40 or 10w40. Id think a 10w50 would shear down to a 40wt anyways.

 

[Propflux01]

Originally Posted By: GMBoy
Originally Posted By: beanoil
10/40. Too much viscosity spread for me in a shared sump motor to run a 10/50. In fact, I'd go to a 15/40 HDEO in that engine and call it a day.



THIS.


+1

 

[vortex9]

Thanks everyone. I guess I will give Shell Rotella 15w40 a try.

 

[Propflux01]

I don't think you will be dissapointed.