Dealer flubs oil change - need advice
My wife brought our Light Khaki Limited to the dealer we bought the car from for the 6,000 mile oil change and service on May 10th. Dealer has the car much of the day. She picks it up and all seems well. We took the truck out to Pennsylvania for the Mothers Day weekend and she drove it as usual over the last ten days, much of it in the rain since it's been a wet spring here. She noticed yesterday that the warning light came on indicating low washer fluid--odd, don't they top that off as part of service? Well, we have a jug of it in the garage, and her being a pilot, she says, she'll top it up. She opens the hood and reaches to open the yellow washer fluid cap, but a black cap sitting upside down on the battery catches her eye. What's this she asks out loud? I come over, we pick it up and flip it over and it see "5W20"--our eyes immediately bolt over to the oil filler, which has no cap on it--they left the cap off!!!!???? Mileage on truck is now 7,200. So we drove 1,200 miles with the oil fill cap off!!! Fortunately, I see no evidence of any stray oil--none on top of the engine, none on underside of hood, and I took a dipstick reading and it shows level within limits, so somehow it all stayed in there.
The big question--what did this do to our engine (it's a Hemi)? Should we immediately do another oil change? Did this hurt my gas mileage during the 10 days? This dealer makes a big deal all the time about how their service is "5 star" and they expect top grades on each service survey. How much of a big deal whould I make of this with the dealer? I'm inclined to, at a minimum, write a letter to them documenting this, so that if the engine fails for lubrication related reasons while we own the truck, I will want it made right on their dime.