As of this writing, our Cascadia, Celeste, is at 225,000 miles on the odometer. At 225,000 miles, it’s now time for Celeste’s third oil change with the DD15 engine. The oil change interval for the DD15 engine in efficient long haul service is 75,000 miles, which also corresponds with the fuel filter change as well. Back in the day, when oil change intervals were much shorter, it was common to replace the rod and main bearings of an engine at 250,000 miles, and have a complete overhaul at around 500,000 miles. On the DD15, however, 500,000 miles only means that it’s time to have an overhead run, to set the valve lash.
Of interest at a truck show this year, I met a gentleman who traded in his Cascadia, powered by a Detroit DD15, who had managed to log 1.7 million miles without an overhaul. Of course, I asked where he had traded his truck in and as luck would have it, I knew the salesman there. I called and verified that this feat was in fact, true.
But back to the main story, which is a performance update on our Cascadia. There have been 3 oil changes and 9 greasings, but other than that, it has given me trouble-free service. I would report to you on tire wear, but due to some bad luck, tires have had to be replaced. I’ve had extensive damage to tires due to road hazards, but not much tread wear. Of course, there was one windshield replaced, which seems to be par for the course living in oil field country.
The lifetime fuel mileage average for Celeste, at this point, is 10.25 mpg. I truly believe it would be possible to have this fuel mileage number at 11 miles to the gallon, or more, if I limited my top road speed to 65 mph. As it turns out, to complete my routes in a timely manner, taking advantage of the 75 mph speed limit in Texas, along with the 70 mph max speed in most of the other states that I travel through, becomes necessary.
During the last 75,000 miles, I have completed two missions, which yielded some interesting results. The first one, you can read the details in a blog called “4 Weeks, 3 Axles”. This venture yielded an 11.72 mpg average. I called this run the Garden State Express as it ran from Laredo, Texas to Swedesboro, NJ, 28 miles of deadhead to Newark, Delaware, and then right back to Laredo. The mileage for this trip is 3,840 miles round trip. This is why I needed to take advantage of the higher speed limits once I got into the southern states, where 70 mph was average, and finally finishing up in Texas with its 75 mph speed limit. To finish my task, without having to take a 34-hour restart out on the road, also required making sure that my timing with traffic was correct when encountering the major cities along my route.
Of course, the Garden State Express run led to many people on social media wanting to know what Celeste’s fuel mileage would be under more demanding duty cycles. This led to the formation of a route we dubbed “The Motor City Express”. This route consisted of heavier loads, along with crossing the Appalachian Mountains, and yielded a fuel mileage of 10.05. The reality of this endeavor was the results did not turn out as expected, because traffic was so bad on the light leg of this run, that the fuel mileage was better in the more demanding sections of this route.
All in all, I have been very pleased with the adaptability that Celeste has afforded my operation with the DD15 engine, DT12 AMT transmission, and the Hendrickson OPTIMAAX liftable pusher rear suspension.
Having all the right parts and pieces from the Michelin wide-base single tires, to the Detroit DD15 engine, which makes the sleek exterior of the Cascadia flow through the air, all leads to the versatility and efficiency that this unit has afforded my operation.
Complete specs for our Cascadia are available on this page for your review.
