lost compression is not a simple problem to attack.
e.g. leaking valves will lower compression and no liquid can help you. OTOH if your compression rings are clogged from running cheap engine oil and bad fuel you can choose a powerful solvent to break that sludge to free up the rings and "hope" the system rebuilds itself (usually theres a very slim chance) - If your engine was run cold the cylinders would be worn down.
firstly determine what is leaking then get to work.