Thickening oils

[KW]

Wouldn't an oil that thickend some be better for an M/C? Don't most bikes shear the oil back to all most water in short order.

What made me think of this was in another thread it was said that a 5W40 would be More prone to thicken than a 10W40. Seems to me one that thickend some would be better than one that sheared all the polymors up and thinned out a lot.

 

[Mickey_M]

quote:

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Originally posted by KW:
Wouldn't an oil that thickend some be better for an M/C? Don't most bikes shear the oil back to all most water in short order.

What made me think of this was in another thread it was said that a 5W40 would be More prone to thicken than a 10W40. Seems to me one that thickend some would be better than one that sheared all the polymors up and thinned out a lot.

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Usually when you select a viscosity of motor oil, you do it with the idea that the viscosity you bought is the one you need.

The solution is to buy a shear resistant motor oil for use in a motorcycle where it also lubes the transmission, the combination of which is a pretty grueling shearing regime.

Mobil, for example, makes two motorcycle oils - a 20W-50 and a 10W-40 - the first of which has no VI booster and the second of which has very little of an extremely shear resistant VI improver.

These oils are extremely shear resistant, so what you buy is what you get, and what you keep.

 

[Jay]

Motorcyle manufacturers already factor shearing into their viscosity recommendations, so I'd stick with the recommended viscosity.

I run Delvac 1 5w-40 in my bike, and this oil shears to a mid 30-weight in less than 1000 miles, so I disagree with your contention that a 5w-40 will thicken.

 

[KW]

That is the part I picked up in another thread and what sparked my question. msparks said that a 5W40 would thicken more than a 10W40. So I thought I would start another thread and ask about it.

It seems to me that a 10W oil would shear less than a 5W oil of the same type.

Jay, does the Delvac thicken back up latter on?