DW and I disagree about how to proceed (that's a bit of an understatement).
What is your disagreement about how to proceed? How do you want to proceed? Something tells me this is the problem. The only solution is for Jiffy Lube to repair or replace your engine. Of course they’ll try to dodge this. You just push back.
Side question: why do men absolutely sprint into “she’s blaming me, waaaaah!” mode. If you were handling this, there’d be nothing to blame on you. So just handle it. What’s hard about this?