Some detergents will etch aluminum alloy unless its washed off very quickly, they are great for removing oil to get parts squeaky clean but thats about all. Hot antifreeze is good for loosening oil residue. Cylinder liners will almost always be stuck and can be safely freed by heating the case and pushing it out with fingers or a stick. I just wear a glove and use a small propane torch. With practice you will be able to completely strip and clean an engine without leaving any signs that it was ever touched.