OK guys so i need to know if i have a case here. I took my car to jiffy lube for an oil change and my owners manual for my car specifically says 5w30 0r 5w40 synthetic only. They put 5W20 synthetic in my acr and a month later my engine is done. My question is do i have a case. Will the use of the wrong oil with the wrong visciouscity cause such a thing to happen. Its a 2000 BMW with 120000 miles. please advise .