Oil change every 2500 miles....1500under severe conditions.
Change Air Filter once a year
Fuel Filter change twice a year
Keep battery terminals on both batteries clean
Use Diesel Fuel with a cetane rating above 42
Try not to let the fuel tank get below 1/2 full unless engine is constantly running...long trips etc...Get Fuel from stations that consantly sell it (Truck Stops etc.)
....Oh, any fuel additive must say "For Diesel Engines"
Glow plugs last a long long long time(See Troubleshooting section)