Оригинальный сообщение: Duane Donaldson ,
Imagine your oil is acting as a seal to seal your piston rings to your cylinder wall gap. Once oil starts to get gas mixed in with it, it looses viscosity and becomes very thin like water and allows more gas in at an exponential rate. This normally happens on vehicles with poor oil change history. Engines running rich with way too much fuel in the cylinders will also act in this fashion as mentioned in the comments above along with piston rings and cylinder wall damage causing low compression where fresh oil will not be enough to seal up the gap. Figuring out if there is an over fuel condition or a worn out cylinder condition is your next step, performing a compression test with gas in the oil will not prove out a weak cylinder, do a wet cylinder compression test by putting some fresh oil in the spark plug hole and see if it will help seal the gap from the top and disable the fuel from entering the engine completely.