DALLAS – Dallas-based Stevens Transport is now approaching 200,000 miles between oil changes, reports Trucking Online. Stevens’ fleet’s maintenance management folks are confident these super-long oil drains are safe and not harming engine life. The 1,600-truck Stevens fleet is mostly Kenworths and a few Peterbilts, all with Cat C15 engines. A six-oz oil sample is taken every 30,000 miles or so and sent to Holt Caterpillar’s lab in San Antonio. The oil analysis on each engine identifies parts per million of brass, copper, aluminum, and other wear materials. It also shows if there’s any antifreeze or fuel dilution. There’s a lifelong database on each engine, and if any sample shows out of the norm, that engine is flagged as soon as possible for an oil and filter change. Stevens had been changing oil and filters about every 30,000 miles, which is five or six times a year in this extremely high-mileage fleet. A test program started in March 2003 when Eric Smith, the company’s director of maintenance, began evaluating a new type of bypass oil filter that filters oil down to the 1-2 micron level and also boils away non-solid contaminants before returning the oil to the crankcase. The first truck in the test ran 70,000 miles, more than twice Stevens’ regular drain interval, before its first drain. Playing it conservatively, even with the positive oil analysis, Stevens then moved the second test truck to 140,000 miles with good results, reports Trucking Online. The third test truck went to 192,000 miles before oil analysis signaled time for a change. Based on these results after more than a year of tests, Smith decided to change the entire fleet over to the new system, doing about 50 engines per month. More than 700 installations have been completed to date. Stevens is projecting an 80-percent oil maintenance cost savings per truck per year, with total savings expected to be at least $1 million annually for the fleet. The filter is sold directly by the manufacturer, Oil Purification Systems Inc.