Mitsubishi has recommended to lower oil viscosity to 5w-30 synthetic motor oil with a CJ-4 API certification. CJ-4 oil is designed especially for high speed four stroke cycle diesel engines with 2010 and newer model year on-highway exhaust emissions standards. CJ-4 oil is formulated for use in all applications with diesel fuels ranging in sulfur content up to 500ppm (0.5% by weight). This classification of oil is especially effective at sustaining emission control system durability where particulate filters and other advance after treatment systems are used. Optimum protection is provided for control of catalyst poisoning, particulate filter blocking, engine wear, piston deposits, low and high-temperature stability, soot handling abilities, oxidative thickening, foaming, and viscosity loss due to shear.
Converting to synthetic oil has several advantages, from keeping pistons cleaner to providing advanced engine friction protection (protects against horsepower loss, potentially fuel economy), to improving engine emissions system protection. The biggest advantage from this change is its ability to better protect the engine against extreme cold by providing faster low oil temperature flow, and against extreme heat by resisting degradation due to internal engine heat pressure.
Reducing the viscosity from 15w-40 to 5w-30 further enhances engine protection by improving cold start oil flow in all temperature ranges
Tom’s Truck Center has seen some of the 4P10 engines with broken plastic timing chain guard, making it necessary to replace the timing chains and guards, always change the tensioners , when repairing these trucks. It is imperative to change the oil and use the correct oil after servicing the timing chains.
Information Packet on timing chain replacement procedure is available at: HERE.