01-27-2019, 09:27 AM
In general the lubricity of diesel fuel has gotten worse over the years correlating closely with the reduced sulfur limits. Good lubricity quality of diesel fuel is critical for all diesel engines, and especially for high pressure fuel systems. To meet lubricity requirements with ultra low sulfer diesel requires the use of additives or biodiesel. Additives are very expensive so distributors try to add "just enough". Biodiesel in general has very good lubricity and the addition of 1 to 3 percent biodiesel is all it takes to get good lubricity for the finished blend.
By law diesel fuel must meet a lubricity spec of 520 using an ASTM (American Society of Testing Materials, which is now officially ASTM International) test method. This spec is like a golf score, the lower the number the better. Unfortunately this legal limit is worse than what most engine manufacturers want, which is 460. From the samples we run it is rare for diesel fuel to hit the 460 number unless it is a biodiesel blend. So in general it is safe to say "legal" diesel fuel may be causing wear at a rate which exceeds the engine manufacturers expectations.
Those of you who are nervous about biodiesel in cold weather, shouldn't be. Minnesota, one of the coldest states in America requires 5% biodiesel in the winter and 20% in the summer. Most states don't require labeling of biodiesel blends until they reach 5% or more biodiesel, so you're probably already used it without knowing.
In coming years when you see "premium" diesel at the pump you can expect better lubricity, better cold weather operability, and better cetane than what regular diesel will have . However when you see "premium" diesel advertised today it may or may not be better than regular diesel there are no set specs for it in many areas of the country but hopefully that will change soon.
So as far as longevity of your engine, especially the fuel system, good filtration of the fuel and good lubricity of the fuel are very important, but are frequently given little attention.
By law diesel fuel must meet a lubricity spec of 520 using an ASTM (American Society of Testing Materials, which is now officially ASTM International) test method. This spec is like a golf score, the lower the number the better. Unfortunately this legal limit is worse than what most engine manufacturers want, which is 460. From the samples we run it is rare for diesel fuel to hit the 460 number unless it is a biodiesel blend. So in general it is safe to say "legal" diesel fuel may be causing wear at a rate which exceeds the engine manufacturers expectations.
Those of you who are nervous about biodiesel in cold weather, shouldn't be. Minnesota, one of the coldest states in America requires 5% biodiesel in the winter and 20% in the summer. Most states don't require labeling of biodiesel blends until they reach 5% or more biodiesel, so you're probably already used it without knowing.
In coming years when you see "premium" diesel at the pump you can expect better lubricity, better cold weather operability, and better cetane than what regular diesel will have . However when you see "premium" diesel advertised today it may or may not be better than regular diesel there are no set specs for it in many areas of the country but hopefully that will change soon.
So as far as longevity of your engine, especially the fuel system, good filtration of the fuel and good lubricity of the fuel are very important, but are frequently given little attention.