STP® Engine Stop Leak is formulated with a special agent to renew polymer seals and gaskets damaged by the heat of normal engine operation, which can otherwise result in oil leaks and expensive mechanical work. STP® Engine Stop Leak will also increase the protection offered by the existing engine oil. It helps stop minor oil leaks, conditions engine seals, and is compatible with regular and synthetic motor oils. It contains no solids to clog filters or inhibit flow, will not harm oxygen sensors or catalytic converters, and can be used in both petrol and diesel engines. Suitable for front and rear main bearing seals, pan and valve cover gaskets, timing gear covers, and other oil seals. To use, add the entire contents to 4-5 litres of engine oil (approximately 15% treat rate), and let the engine run for 15 minutes.