Originally Posted by devarshi84
2. My bullet has a shared sump vs. a separate sump on many British vintage motorcycles. Thicker oil is definitely needed.
Think again... Blackstone Labs data shows thin is in...
The Importance of Viscosity?
Quote Blackstone Labs
The viscosity, or thickness of the oil, is not nearly as important
as many people think. Oil retains its nature no matter what thickness
it is.Think about this: automakers are continually recommending
lighter multi-grade oil in new engines. The reason is increased
efficiency. It takes power to pump oil through an engine, and the
lighter the oil, the less power required to pump it. The oil's ability
to act like a solid and protect parts is not related to its thickness.
If that doesn't sound quite right, consider this: The gears in a
heavy duty Allison automatic transmission are doing the same work as
the same machine equipped with an Eaton manual transmission. Due to
the hydraulics of the automatic, it runs on a 10W automatic
transmission oil.But the manual transmission uses a very thick
(sometimes up to 90W)gear lube oil. The gears of both types of
transmissions will have a similar life span. We don't find any
significant differences in wear, regardless of oil thickness.
Quote 540Rat
VISCOSITY vs WEAR PROTECTION CAPABILITY COMPARISON:
20 wt oils rank between number 2 and 220
30 wt oils rank between number 1 and 233
40 wt oils rank between number 6 and 219
50 wt oils rank between number 39 and 228
60 wt oil, the only one tested, ranked number 101
70 wt oil, the only one tested, ranked number 177
So, as you can see, this is absolute PROOF that viscosity does NOT
determine an oil's wear protection capability, even though many people
mistakenly believe it does. As mentioned above, an oil's wear
protection capability is determined by its base oil and its additive
package "as a whole", with the primary emphasis on the additive
package, which contains the critical extreme pressure anti-wear
components. And the additive package has nothing to do with viscosity.
In general, it is best to use the thinnest viscosity motor oil that
will still maintain sufficient HOT oil pressure. Thinner oil is best
because thinner oil flows, lubricates and cools critical engine
components better than thicker oils can. Thinner oils reduce bearing
temperatures and sump temperatures compared to thicker oils. Thinner
oils can also help increase horsepower and miles per gallon. Using
thicker oil than is needed, is going the wrong way.