Oil Viscosity? What's Best

[Lubrecon]

Al and Ron: I am not worried about my manhood, whatever that is. Look guys here is what an engine oil does in the engine, cylinders, bearings, camshaft area, everywhere. This not necessarily in the order of importance. First it lubricates, then reduces friction, then it reduces wear, then it cools, then it seals, then it cleans. It is not absorbed into the metal, anywhere. Metals, including cast iron are solids, they don't have pores. What the do have are asperities, the peaks and valleys on the surface of the metal left from machining. Ever heard of surface finish? Its designated by RMS, which means Root Mean Square, it is the roughness or smoothness of the surface. At the microscopic level all metallic surfaces have asperities. What you would ideally want is for all asperities to be separated by a full fluid flim of oil. This is call hydrodynamic lubrication and happens mostly in the bearing areas, main, rod, cam. There is a flooded supply of oil. Some takes place in the ring zone area also, except at the top of the stroke when the piston reverses and goes back down the cylinder. At the top, there is very little, if any oil to lubricate or separate the ring face from the cylinder wall. At this point, the lubrication is called boundary lubrication, and the surface chemistry, as affected by the additive components in the oil, namely antiwear additives, protect the surfaces from excessive wear. The actual oil at this point is secondary. Under boundary lubrication, actual metal welding takes place and wear is minimized by the surface chemistry. The surfaces now have materials on them that shear easily and minimize the welding and tearing that is taking place. Bounday lubrication also occurs in the camshaft area. Thats why when you frictionally modify an oil with solids(PTFE, moly, graphite) or some other chemical such chlorine, you get reduced friction and wear in those areas. You also pick up some HP increase, small of course, but some nonetheless. There may be some oil trapped in the asperities at the top of the stroke, and it would be consumed, but it is not leading to or causing any cylinder glazing that makes a smoother surface and reduces friction. There is a phenomenon in diesels called bore polishing that is a result of the soot in the oil, but that is an unwanted happening and leads to many engine problems, not for this discussion.

Bob, help me out here, I have to go to bed. More tomorrow if needed.

BTW, my name is Jerry Shelby. BinB want proof??