15W-40 motor oil
What is 15W-40 oil used for? 15W-40 is a very common viscosity grade for diesel engine oil. GTX Diesel is a 15W-40 diesel engine oil formulated to help extend engine life.
What is the best 15W-40 oil to use?
If you need a 15W-40 diesel oil, Castrol® GTX® Diesel helps extend engine life, protecting against the wear and tear of severe weather, rough roads and heavy tows. As a 15W-40 viscosity grade, it flows like a 15 weight oil from start up in Winter, but provides the protection of a 40 weight once the engine reaches full operating temperature.
