What Makes a Good High Mileage Truck?

The modern definition of low mileage truck would seem ridiculous just 20 years ago. Since engines are so high-tech and computerized, and modern suspensions help preserve delicate electronics, we now have engines with 350,000 to 450,000 miles logged that can be classified as moderately low mileage. Transmissions are warranted to well over 500,000 miles. The development of synthetic lube allows trucks now run 250,000 miles between changes. In the past, that many miles meant the end of the road. These days it just means a quick change and you’re on your way.

What truly makes a high-mileage truck a good buy is when the owner keeps regular, proper maintenance and inspections. This extends the operating life of Class 8 trucks tremendously. Along with these developments is a change in the used truck buyer’s perception of what is a low-mileage truck. You just can’t expect to walk onto a sales lot and ask for a truck just a few years old and expect 150,000 miles on the odometer.

Go back a few decades when warranties expired at 100,000 miles, a truck that’s logged 4 or 5x that much was classified as a high-mileage truck in need of overhaul. Typically the owner would trade in his trucks at 200,000-300,000 miles. These days, it’s not unusual to see nearly-new trucks with that kind of mileage on them with a hefty resale price.

But let’s be honest; the number of miles rarely has anything to do with a truck’s dependability and roadworthiness. The warranty period has nothing to do with the dependability and quality of the tractor. It’s the care and diligent maintenance provided by the owner. Otherwise the general rule of thumb is that a truck with 3x the warranty coverage miles should be considered a high-mileage truck. But these days, that means we could be speaking about a truck that’s logged nearly 1,500,000 miles. We can chalk this up to the incredible changes in powertrains and other vital components of Class 8 tractors.

Evolution of Engines

With the birth of electronically controlled engines in 1987, a new era in diesel engine manufacturing, operation and maintenance began. The modern electronic engine is a work of art. Engine computerization is the most obvious and major change in technology that has   improved engines and provided extended life of Class 8 trucks.

New technological developments allow engine protection systems not only sense and protect the power plant from failure but also log all performance data recorded by electronic sensors. The electronically-controlled combinations of power and fuel economy fine tune the efficiency of engines resulting in improved safety records, improved driver performance and recorded and reduced maintenance expense. All 5 major manufacturers build their engines with this controlled management approach that has virtually eliminated catastrophic failures for the first year.

To allow a truck to be maintained at a lower cost and be on the road more, parts had to be redesigned to extend maintenance intervals without compromising the overall life. The major 5 builders have evolved their engine lines to an incredible degree, which should make buyers of tractor trailers that even have 4x the warranty miles feel a bit easier about their purchase.

Next installment, we’ll speak more about the evolution of robust and reliable engines, new developments in transmissions and rear ends. Stay tuned!