Motor oil in place of chain oil will leave you with a cleaner looking bar and chain because it isn't designed to cling to the metal as much as the chain oil is. The bits of tree aren't doing any harm, just indicating that your chain and bar are coated with oil as intended. Using motor oil is better than nothing, but chain oil is better for the purpose as long as you cut only wood. If you occasionally saw dirt by mistake, or cut logs that have been dragged and have a lot of dirt in the bark and such, the motor oil might be better than the bar and chain.
How well does Mr. Funnel work at filtering out the dirt from lube or hydraulic oil? Has anyone tried it? I just took my old oils to be recycled at Advanced Auto Parts. They accepted it, but they don't give you anything for it.
My manual calls for either 15W - 40 or 10W - 30 in the crankcase. The stores around here don't seem to have 10W - 30 diesel grade oil. The manual doesn't specify heavy duty or diesel grade, just 10W - 30 and 15W - 40. Do you guys all use heavy duty diesel grade motor oil?