Kit Includes: Universal block tester, 16 ounces of test fluid and complete instructionsTests for: Cracked blocks, leaky gaskets, cracked or warped headsFluid turns from blue to yellow if combustion leak is presentUse when condition of engine is unknown, engine starts hard, cylinder head has been removed, engine overheats, loss of coolant occurs, rusty radiator conditions are present, before engine tune-ups or cracked block or head gasket problems ars suspected Applications: Liquid cooled internal combustion engines and generators, all fuels, gasoline, diesel propane and alcohol