350,000 miles is high mileage for a diesel truck.
Diesel Trucks with the Diesel engines tend to last longer than trucks with gasoline engines.
Some diesel engines and diesel trucks can last as long as 1 million miles and sometimes more if taken care of properly.
Once the diesel truck gets to 1 million miles or more then the diesel truck becomes less reliable.
However you can then replace the diesel engine with a new one and also rebuild or replace the transmission and get many more miles out of the truck.
As for what's considered high mileage for specific diesel engines?
Anything over 350,000-miles is considered high mileage for a used diesel pickup with a Cummins or Duramax engine under its hood.
Anything over 350,000-miles is also regarded as high mileage for a Powerstroke diesel engine
Diesel trucks such as Powerstroke, Cummins, and Duramax typically last well beyond 100,000 miles even when used extensively for towing and hauling.
As a result, diesel trucks with 200,000 and even 300,000 miles are often very valuable on the used truck market because of their resale value.
Not only can diesels haul heavier loads, but they can also do it more efficiently, saving on fuel.
That's why they're the perfect trucks for work-related or recreational use.
They can handle tough challenges on the job, and they can also tow sport vehicles, trailers, or campers without hesitation.
Diesel maintenance is cheaper overall, since diesel engines have fewer problems than gas engines; but diesels are more expensive when they need repairs.
Diesel maintenance generally will not cost you more than for a gasoline powered version, depending upon the type of diesel car that you have.