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
The engine oil level should be checked few minutes after the ignition switch is turned off.
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