| Its the difference between skiing on water vs. molasses. What keeps the bearings from contacting the journals is the difference in the velocity between the two. That difference in velocity causes the bearing to "plane" on the oil. The oil can only handle so much pressure from the bearing before the bearing bottoms out. Think of the bearing like a skim board and the oil like the water, the journal being the ground beneath the water level. What keeps the skim board in plane is its velocity and surface area. We can't increase the surface area of our "board" (i.e. the bearing) but if we use thicker oil, it will allow us to support the weight of a heavier rider at the same speed. Heavier rider, of course, the analogy to greater force placed on the bearing. 10W oils are just too thin to support higher power levels. It is great for fuel economy and a stock TT but when you start cranking up the power you cannot get away with lighter oils and expect the bearings to survive long. There is an argument that thicker oil reduces flow, and that is a misnomer. Our oil pumps are mechanical gear pumps and oil is incompressible. Every rotation of the gear pump displaces the same amount of oil regardless of oil weight. In fact, it can be argued that the thicker the oil, the less pumping loss there is in the pump itself because the thicker oil has more difficulty bleeding through the small clearances between the gear teeth mesh, the gear teeth-housing clearance, and the gear face-housing clearances.
Enthusiasts soon understand each other. --W. Irving.
Are you an enthusiast? If you are out to describe the truth, leave elegance to the
tailor.
Albert Einstein
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