I took my Buick Lucerne to a Firestone for an oil change about two years ago one time and a mile away after the “service” the change oil light came on. I pulled over and checked the oil level and it was completely dry! It was like they drained the old oil but didn’t put any new back in! Needless to say it was the last time I went there!
I’m still convinced too they are the reason a year later the engine started missing and eventually failed catastrophically. I could never prove it though.
Back in the late 80’s I was driving a brand new company car back from Santa Cruze down HW 17 into Los Gatos. Suddenly the engine started knocking and lost all power. Managed to pull over near a phone booth and called a tow truck. When he showed up he checked the oil and showed me it was full. Towed me to a dealership in Los Gatos. While I waited the shop manager checked out the problem bad came to the waiting room holding the dip stick and told me to look, no oil.
Luckily the tow truck driver was just leaving and I waved him down. I asked him to tell the manager about him checking the oil level. He did and the manager turned on his heal and walked off. Broken crank shaft. Ford Granada. Ford replaced the engine. No charge. Never ever trust a dealership.