[NA]Toyota engine[NA]

[Let'sgoflying!]

"Final Settlement" on the stub is unlikely to be effective release; explicit language like (say) "Negotiation constitutes full and final payment of all sums due and owing" or the like might succeed, but even then, it is not likely, especially in a consumer context.

Thanks...I also figured I would have to actually sign something which I didn't (except the check).

For the future use of others, I think I had good results with my claim because:
-good documentation
-having a third party involved (the shop that drained the tank)
-having the shop send me an invoice which stated "gas had a diesel odor"
-including all my observations on a tidy typed letter with letterhead
-never being demanding, or copping attitude, simply stating my suggested resolution, always polite.
-mentioning that I have retained a sample of the suspect liquid.
HAVING A LEGIBLE RECEIPT FROM THAT PURCHASE (many, many places now have inop printers at the pump and you have to go in for it if you want one)