Delo must be good oil. The guy that delivers my paper drives a VW rabbit diesel with Delo oil that has over 400,000 miles with lots of stop and go driving. He changes it once a month regardless of miles. The engine sounds like new. It would be hard to make an argument against using this oil and changing it often.

However with the oil analysis that I have had done does show the synthetic to be superior even at the extended train interval. I also never have to worry about the car starting in cold weather. The mileage increase of 2 miles per gallon pays for the oil in 10,000 miles.