[M.D. Holloway]

Sing - motocycle oil is unique due to the clutch. The oil actually has to maintain a certian "grippyness" (thats the technical term). Actually the technology is somewhat similar to ATF fluid in that the balence between the co eff of friction v. the co eff of lubricity have to have a certain balence and if you upset that balence than you can feel it when you shift. Eventually you will get premature clutch wear if the oil is sub-par. The fact that you are getting a black sunstance at the bottom of the pan is troubling. That is sludge for sure. There are a few resons why they develop:
Inferior Base Oil - When the base oil contains one or more of the following; light fractions, sulfur, low molecular weight hydrocarbons.

Insufficient Concentration of Performance Additives- Low concentrations of anti-wear agents and/or friction modifiers produce wear metals and localized frictional heat. Low concentrations of demulsifiers can lead to emulsified oil, which hastens oil oxidation.

Yellow Metals (copper, brass, bronze) - Contaminants from external or internal sources can catalyze oil oxidation and lead to deposits and additive depletion.

Heat - High ambient temperatures, operational heat (from kinetic energy or combustion), frictional heat (from metal to metal contact), pressure (from aeration and/or operation) can accelerate oil oxidation and additive depletion.

Water - By-products of combustion and/or external contaminants can hasten oil oxidation and lead to deposits, additive depletion.

Acids - Develops when base oil breaks down into reactive species, produces sludge, varnish and/or other deposits, or external source such as acid washing. Common forms are sulfuric acid, nitric acid and various carboxylic acids.

Caustics and Solvents External Contamination - breaks the oil molecule into reactive species. The reactive species may polymerize to form resinous deposits.

It is rather interesting how sludge forms. Found in oil pans, sumps, housings, reservoirs, and bearings. The formation begins when contaminants begin to settle out of the oil. Sludge develops with excessive accumulation of contaminants leading to additive depletion and oxidation. Sludge is composed of water, carbon residue, oxidized oil, and acidic compounds which can lead to further oil decomposition. It can restrict oil flow leading to increase system pressure, temperature, wear, and oil viscosity increase. Not a good thing.

I can get you oil analysis through a great lab (which I have nothing to do with) for about $15 a test. If you get 10+ tests I think I can get it down to $10 each. If your interested, let me know.

I should get Wayne to offer these through Pelican.