[TGTIW]

Hopefully someone here could help me out a little. My mother-in-law took her car (05 Ford 500) to be washed and serviced. The place (a full service gas station) washed the car and then also filled it with 15 gallons of diesel fuel. Long story short, the car dies, goes to the dealer yesterday, dealer says it's got diesel fuel in it, they go back to the station and after a little arguing the station admits to putting diesel in and says they will take care of any mechanical bills. The Ford dealer drains the tank and says the car will run a little rough for a while, but it should be fine. Would it be a good idea to have the fuel filter changed and maybe a fuel system clean performed? Also, would filling it with diesel void the engine warranty (it has 28,000miles)? Do you think it's worth the hassel to pursue legal action for a percieved loss of value? Any suggestions are welcome.
Thanks.