Bottom Line
Maintenance Q&A
Prepping for a million miles and beyond

By Paul Abelson
Senior technical editor


Q: I am an owner-operator running flatbed locally in Atlanta. I own a ’97 Freightliner Century Class with a 12.7-liter, 430/470 Detroit. The motor has around 970,000 on it with no rebuild.

The heads and No. 6 cylinder were rebuilt at about 730,000 miles. It was an unnecessary fix because of a misdiagnosis. At that time the rest of the mains were inspected. They looked good.

I have it serviced every 15,000 miles with Rotella T and factory filters and have never used any oil additives. I have never had an oil analysis. The truck has given me great service, but with the motor approaching a million miles, I’m apprehensive about taking it over the road. My local work has dried up, so I have to try something else.

How do you recommend I keep my truck going since a newer one is not an option? I see some additive and bypass filter ads that boast extremely high mileage performance and wonder whether any are legitimate. If any of the products are the real deal, I would like to know.

A: You are wise to prepare your truck to exceed 1 million miles in case you need to change jobs to keep up with economic conditions. You have a good platform to work with. Since the early 1990s, many Detroit Series 60 engines have regularly exceeded a million miles.

You should get an oil analysis before anything else. It will give you a snapshot of your engine’s condition, and provide a baseline for determining future engine wear. TMC has a lengthy discussion on how to use and interpret oil analysis. Recommended Practice RP318B, Used Engine Oil Analysis, is an eight-page document covering all aspects, from taking samples to interpreting results. The amounts of specific wear metals in the oil will tell you what, if anything, you might need to repair or replace to extend engine life. Different metals indicate which engine parts may be worn: iron for cylinder liners, cams and valves; chromium for rings; copper and lead for bearings, etc.

If you determine that wear metals are within limits and the engine is running well, put a reputable high-detergent fuel conditioner through the fuel system. Howes, Power Service, FPPF, Penray and Lucas are well-known and respected brands. Follow directions on the container. Then check compression and set the valves. A computer diagnosis should tell you whether the injectors are still good. Replace them if they are out of specification.

Once you’ve determined your engine is worth spending more money, consider a bypass filter system. I’m partial to those using highly tensioned, rolled-up filter material rather than compressed fibrous waste. Gulf Coast Filters, Harvard Corp. and Como Industrial Equipment make very effective units that will capture soot and wear metals down to two or three microns, that’s 10 percent smaller than the particle size trapped by the best full-flow filters.

You should be able to pay for the bypass filters by extending oil drain intervals, but not without regular oil analysis. TMC RP334A, Guidelines for Establishing Proper Engine Oil Drain Intervals for Heavy-Duty Diesels, describes procedures to determine when to drain. If you can double your interval from 15,000 to 30,000 miles, common with bypass filters, you can save four or more oil changes per year. At $150, that’s payback in less than two years. By eliminating fine abrasive particles, you’ll be dramatically reducing any further engine wear.

 Oil manufacturers recommend against using additives with their carefully formulated blends of base stocks and additives. And the oil you’re using, Shell’s Rotella T, is recognized as one of the better premium oils. But I’ve heard high praise about some oil additives, especially Lucas. I know it won’t hurt, and it could help prolong engine life.

The key to prolonging your truck’s life is maintenance. Make sure your chassis, suspension and drivetrain are as good as your engine. LL


Paul Abelson can be reached at