Castrol Power 1 4T 10W30 Part Synthetic Motorcycle Oil. Part Synthetic 4-stroke engine oil with Trizone Technology, Exceeds JASO MA-2 and API SJ. Castrol Motorcycle Engine Oil Applications. Castrol Power 1 4T is designed for the latest generation of sport, touring and on-off road bikes from leading European and Japanese manufacturers. 10W-30 has been developed for engines that specifically require a low viscosity lubricant. 10W-40 is suitable for high performance bikes including highly stressed multi cylinder units. Castrol Motorcycle Oil Increased Power. Oil flowing round the integral engine, clutch and gearbox of a modern motorcycle engine can contribute to internal drag and friction, which can ultimately reduce power output: Castrol Power 1 GPS 4T has been specifically designed to reduce them: Castrol Power 1 GPS 4T can deliver up to 3.0 % power increase when compared to conventional engine oils. Tested using a highly stressed 4-stroke motorcycle engine operating at maximum rpm.