Never underestimate the importance of engine oil. Keeping it clean, even in a diesel that holds 10-15 quarts is key to long, durable engine life.

In my case, oil is responsible for actuating my fuel injectors (7.3L Power Stroke), and is regularly subjected to injection oil pressures anywhere from 500 to 3,000 PSI. Knowing this, I have always gone with one of the most familiar oils used in diesel engines, 15W-40 Shell Rotella T. And, while I’ve never considered using a different oil, maybe there are better out there.

The truth is, most truck owners will tell you the oil they put in their diesel is the best, and would recommend you use the same in yours. Along the same lines, I’m sure that Ford would recommend only using their Motorcraft oil, GM would only recommend their Duramax-specific oil and every other oil company will claim that there product is the best on the market. For example, Amsoil claims its synthetic blend keeps engines cleaner than every oil offered, and a quick search for “best diesel engine oils” on yahoo returned 5 (of 10) sites related to Amsoil. Still, does this make it the best? What oil do you prefer in your truck?