If we had to pick the most frequent cause of diesel engine failure, we would choose antifreeze, the killer extraordinaire. There are several ways coolant can get into the oil — head seals, pin holes in wet liners, injector cups on some types of engines, and the oil cooler. By the time you see discolored oil, the problem has very likely progressed beyond a point of economical repair.

Fuel dilution problems run a close second. Bad injectors and fuel pumps can dump serious levels of fuel into the oil sump, affecting the oil's ability to function properly. Left undetected, a fuel system problem can cause catastrophic engine failure.

These are just a few of the problems faced by diesel engine owners. Preventive maintenance can help you avoid costly repairs. Send us a sample of your used oil for an in-depth look at your diesel engine.

About TBNs