It is easy to fill a diesel with unleaded. The unleaded nozzle is much smaller than the diesel filler opening. Not to mention, most self-service stations today use the same size nozzle for both pumps. Only the stations that cater to truckers provide the larger nozzles on diesel pumps. This allows for faster filling of the tank, not to prevent the unleaded user from getting the nozzle in his tank.
Mixing unleaded into a diesel engine can lead to detonation of the engine. If allowed to run for a prolonged time in this condition, the engine and injection pump could both be damaged. An excessive 'knocking' noise would be an indication that something is drastically wrong.
I would not be overly concerned in your case, due to the low percentage of unleaded. You can always drain or siphon the tank if you are worried about it. DEFINATELY be aware of unusual knocking, this could indicate that the damage has been done!
If you do not drain the tank, then stop at every station you can and add a gallon or two for the next few weeks. After that you should be safe to run it dry before filling up with the "good" stuff.
The one who's daughter filled up her diesel with unleaded was Larry Bible. You have a good memory because that was about 15 months ago.
Last edited by WmHarlow; 06-04-2002 at 04:14 PM.