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Fuel Is the Enemy of Your Diesel Engine

By Total Seal

Fuel is the enemy of your diesel engine. Specifically, unburnt diesel fuel is the enemy. When diesel fuel doesn't burn, one of two bad things happens. The unburnt fuel goes past the rings and mixes with the oil, or the fuel carbonizes, which creates soot. The black smoke coming out of the exhaust is actually not smoke--it's soot.  

Why are both of these bad? How could they be the worst things for the engine? Simply put, they are both contaminants, and contamination is the actual number one reason for premature engine failure.

Liquid fuel that gets past the piston rings dilutes the viscosity of the oil, and oil viscosity is the most important characteristic of a lubricant. When the viscosity drops due to high fuel dilution, engine wear increases. A failed rod bearing is more likely to have occurred due to fuel dilution than it being a "bad bearing." In fact, used oil analysis shows that as fuel dilution increases, overall engine wear increases, so keeping the fuel out of your oil should be priority number one, especially when building high-horsepower diesels. More power means more fuel, so the more power you are making, the more important it is to prevent excess fuel dilution. 


New Total Seal diesel ring sets are available for Cummins 5.9L and 6.7L; Duramax 6.6L; and Ford Powerstroke 6.4L to 7.3L. Custom sets are also available.

So, what about the unburnt fuel that carbonizes and creates soot? The reason diesel oil turns black is due to the soot in the oil. Here's a little-known fact: Soot is the primary cause of "normal" wear in a diesel engine. In fact, diesel engine manufacturers test their engines with pre-sooted oil to make the engine tests harder. The tiny particles of carbon cause abrasive wear, so diesel oils are formulated specifically to bind up as many of those soot particles as possible and keep them from combining into big, sharp particles that could do a lot of damage. Ever wonder why so many diesel engines used flat tappet cams for so long? One reason is that flat tappets are more resilient to soot-related wear.

Total Seal Gapless Diesel

Total Seal Gapless® Second ring diesel set.

Fortunately, there is something you can do to combat the effects of unburnt fuel. The weapon against your engine's enemy is a Gapless Second piston ring. By eliminating the piston-ring end gap, which is the leak path that allows both the liquid fuel and the soot to get into the oil, you reduce the fuel dilution and soot contamination. Independent engine testing has shown that a Gapless Second ring in a diesel engine increases boost and reduces blow-by at the same time. That proves the physical barrier created by the Gapless piston ring seals what's happening in the combustion chamber from reaching the crankcase. When the liquid fuel and soot are kept out of the oil, the oil works better and lasts longer. In fact, the extra oil life (typically) more than pays for the added cost of the Gapless Second diesel rings.

Total Seal Standard Second Ring

Total Seal Standard Second ring diesel set.

While Gapless rings have been around for a long time, Total Seal now offers complete diesel ring sets that feature their patented Gapless Second ring technology. The Top and Second rings are crafted from Martensitic Ductile Iron, the highest-strength iron available, and they are specially heat-treated before being coated with Chromium Nitride, which is a chemical compound of chromium and nitrogen with the formula CrN. It is very hard and is extremely resistant to corrosion for lasting durability and reduced wear. The patented Total Seal Gapless® Gapless® Second Ring design keeps the fuel and soot out of the oil. Not only do these rings reduce engine wear, but they also reduce turbo lag and increase boost as well. Don't be afraid to vanquish the enemy of your high-performance diesel engine. A Gapless Second is the ring of choice for high-performance or high-efficiency applications.