It is recommended that the injectors removed should be replaced with ones of the same kind due to possible differences in rates of flow between manufacturers. Given the high pressure nature of fuel injection systems, it is important that a careful check be done on fuel injector O-rings, and where applicable, fuel rail feed line O-ring inspection must not be overlooked without any intentions of reusing these if they are brittle, cracked, deformed, compressed or damaged. To facilitate assembling and prevent spoilage of Lube injector o-rings and fuel rail O-ring with fresh oil or petroleum jelly. Specific procedures for various BMW engine types such as S14, M20, M42, M44 850 M52 and 852 include steps like relieving fuel system pressure, disconnecting electrical components and fuel lines; removing Fuel Rails; checking and replacing O-rings when necessary; ensuring similar types of injectors are fitted; then reassembling components in reverse order taking care not to damage valve covers or allow debris to enter while completing this process.