humidity

temperature

vibration

contamination

appears milky

becomes foamy

turns black

none of these

immediately after the ignition switch is turned off

while the engine is running

a few minutes after the ignition switch is turned off

while the engine is running at high idle speed

dilution of fuel in the crank case

dilution of oil by water in the crank case

dilution of lubrication oil by fuel in the crank case

dilution of mixture passing through crank case in two stroke engines

release chamber

balancer

relief valve

stop valve