"I wonder what would 240Joe's take on synth oil would be?"

My take is....go for it! I believe synthetic oil is superior. It saves $ and time.

In addition to the reasons given above, don't forget the ease of starting in cold weather.

Mobil 1 changed every 10kmiles is a safe change interval for our diesels. I'd sample the oil before you try to push it any further using this oil. Soot will be the limiting factor.

I might switch to delvac 1 and push out the change interval to 15 or 20kmiles.

240Joe