Just take out the plugs and let it sit for a while. If the engine has low compression or low compression with the oil washed off of everything, a shot of engine oil in each housing will help with heat of compression or WD-40.

OK; the shot of oil is intuitive – and I’d think perhaps you’d want a shot in each ‘chamber’.

 

In winter I have used several shots (from a pump style oil can) of engine oil and 1/2 cup of hot coffee in each housing.

What does the hot coffee (basically water) do?  I’d think it would just foul the plugs.

 

Al G.