In the most simple terms the best way to take care of any diesel engine is through preventive maintenance. Keeping your air filter clean, regular oil changes, and most importantly waiting until your glow plugs have cycled through will do as much in maintaining your engine as any thing else.
With each fill up at the pump, you should add a bottle of diesel treatment. It can be found at any parts store or in most cases at the same fuel station you get your fuel. Using the diesel treatment help keep the impurities from the fuel and your tank from reaching your diesel engine.
Depending on the mileage, and normal load you carry you can also add a synthetic oil product to your engine on your next oil change, using a synthetic oil can in some cases add extra lubrication and extend your rings and seals.Simple easy steps to keep your Diesel engine running at it's best.