My cousin accidently poured in 5 liters of valvorin maxlife transmission fluid into the engine dipstick hole on 1995 e320. The engine was not cranked or started with the transmission fluid in it. I drained the engine oil/trans oil mixture out of the engine and changed the oil filter. How long should i run the engine before doing another oil change to make sure all the trans fluid is out? SHould I use one of those engine oil drain fluid you use 5 min before an oil change? Any help would be appreciated. ---The engine leaks oil from head gasket, would engine oil drain fluid make it worse?