lastly, my 2cent's worth RE: engine lubrication subject RE: upper cylinder lubrication.
Gone were the days where a rather archaic carburettor to richen the fuel-air mixture during cold starts, where most of the unoptimised carb could literally dump raw fuel into the otherwise cold cylinder inside a cold, cold engine, causing cylinder "wash" where engine oil film was literally dissolved in gasoline and washed down into the crankcase. In those days (carb'ed engine, with poor fuel-air mixing and metering), engine cylinder bore (upper portion) tapering after many tens of thousands of miles were common, due to frequent cylinder wall washout.
Nowadays, fuel metering and high pressure fuel injectors with pre-determined fuel-air mixture ration during cold start up, this cylinder wall "washout" has been greatly minimised. As a result: you don't see a lot of upper cylinder wall wear (tapering) due to lack of lubrication (washed away by unburned gasoline).
No need to feed those mysterious magical elixir that claimed all the miracle-in-the-world when mixed with gas, period. In fact: many other motoring industrialised countries outside of US of A do not even know/aware of such additional need of UCL, and their engines still live many long, long happy service miles.
Go figure.
Q.
