Hydralic lock isn't just a water issue!! an oil do it just as easy!!!
This is how I've always done it.
With a warm engine, dribble water in at a rate just fast enough to regulate the RPM while holding the throttle 1/4 open.
This is steam cleaning the combustion chamber.
never put an oil down the intake passage.
Use a light oil MMO, ATF Diesel in the oil pan 30 minutes before an oil change, and do not drive it very far, if at all. Oil will be too thin to do its job under heavy load.
I have seen the ATF in the intake and it just oils the passages and of course makes it look like the operator has NO CLUE what he is doing, other than killing mosquitos!!!