'Flood the engine with Marvel Mystery Oil
Once you get the ice free, dont wait to suck out the engine oil and then flood the crankcase, combustion chambers, with Marvel Mystery Oil. If you cant find MMO then flooding the engine with automatic transmission oil (ATF) will do. Flooding (with a light oil) the combustion chambers will be the most important as this will prevent the piston rings from rusting/freezing in their grooves. If the piston rings get frozen, you will break the rings when you attempt to start the engine. As another poster stated you want to as soon as possible be able to turn the engine over by HAND to ensure that the piston rings, valve stems, etc. dont 'freeze'. Once you are SURE that the engine can easily turn over by hand and you find NO binding when hand rotating, then with the fuel supply shut off, turn the engine over by the starter with the injectors removed. IF the rings are frozen/rusted, or the engine is 'binding' when you try to rotate, continue to add MMO to the combustion chamber through the removed injectors and simply keep turning the cranshaft back and forth until the engine is 'free' - just be patient and do not FORCE the rings or you will break them. It may take several days of crankshaft rocking and MMO addition ... but eventually the engine WILL break 'free'. Once the engine is free to turn, change the crankcase oil to a mixture of 75%MMO and 25% regular oil .... spin the starter to fill the oil galleries, then start the engine (keep that rag handy in case you need to jam it into the air intake in case of a 'runaway'). Run the engine at idle (NO LOAD ... transmission in NEUTRAL) until warm. This will repolish the cylinder walls and valve stems. If the valve stems are stuck ---- open the valve inspection plate and watch that the valve stems are actually moving up and down and NOT stuck .... if stuck reach into the combustion chamber with a 'tool' and simply push the stuck valve down a few times until free. Do this idle-to-warm sequence several times. Then change the crankcase oil to 75% normal oil and 25% MMO and 's-l-o-w-l-y' over time bring the engine up to speed (NO LOAD - transmission in NEUTRAL, and when sure that the engine is OK then begin with a load on the engine - keep that rag handy in case of 'runaway'. The object is to NOT break the piston rings, but to 'free' the rings .... and get then engine HOT to drive out the accumulated water and drive the 'emulsified' water from the lubrication galleries, etc. Once the engine is 'running' with load, change the oil (detergent oil) several times to be sure that all water is removed .... run the engine until HOT and keep it running to drive out the water. Even if the engine is rust-frozen, do not despair .... just gently keep rocking the crankshaft back and forth until it does break free. DO NOT force the cranks shaft ... as you WILL break the piston rings, just be patient. Once you are pretty sure that you saved the engine ... run it with a NON-detergent oil for a while (to help 'reseat' and re-"break-in" the engine. After about 20-25 hours of run time, change back to you normal oil. The above method will sometimes allow a totally rust-frozen engine to be 'brought back from the dead'. Be patient and do not force ... but as quickly as possible get the engine to run HOT to drive out any remaining water. good luck.