There would have been excessive oil pressure, not low oil pressure. The oil density is not measured by any sensor in the engine.

If you want to physically see what happens to the oil when you overfill the sump, someone posted a YouTube video a few posts earlier of a Russian dude slowly killing a Lada engine with a plexiglass oil pan. As for damage to crankshaft, camshaft and other journal bearings, Google "bearing cavitation erosion". You are pumping a thin, aerated foam that does not have anywhere near the required film strength to lubricate a journal bearing. The only question is how long and how hard (RPM-wise) was the engine run like that and how much damage would have occurred as a result. At 6,000 RPM, the crankshaft makes 100 rotations every second. Have a look at the Lada engine video.

 

Damn!!

 

So sorry to read about this misfortune @ BLKROKT

It's by far not the same thing, but last year I had an incident myself with a shop that I trust(ed) and have a long relationship with. I took my C63 to them for a transmission service. Transmission had been running fine but I noticed it had burped out some fluid from a few HPDEs. Seemed prudent to me to have the fluid replaced. Shop performed the work and I got my car back. Transmission started acting a bit funny then. Tried to convince myself it was normal (afterall these transmissions aren't known for being super smooth) but eventually realized it just was not. Took the car to another shop (one that is a bit more Benz specialized) and asked them to service the transmission. They reported back that the transmission was 2 quarts low on fluid. I mean....COME ON! It was also their opinion that no internal damage had occurred. Original shop then refunded me the cost of the second transmission service (not the cost they had charged me, which was actually less). So good on them for that. But, in the back of my head, I still wonder if something is wrong with my transmission. It just seems to stutter/hesitate way too much when cold.

 

OP...... Bummer it happened. Techs are human. Humans make mistakes. We'd all like to think that an error such as this would be near impossible to make but alas... Here we are. Think for a minute it wouldn't happen at a dealership? Think again.

I'm relieved for you and the repair shop that you don't intend to follow the 'Lawyer route.' Introduce someone; anyone to that unpleasant person by the name of sue and you will immediately find ALL communication STOPS as from that point forward EVERYTHING will be handled via attorneys. What is rule number one with attorneys you ask? I'll help. The Attorneys ALWAYS get paid. Rule #2 is that it will take a long time. Where there is just property damage you are much better off settling this with the repair shop who obviously didn't intend to screw up.

As for real damage having been done to the engine in fifty miles of it having been overfilled with oil.... In all likelihood the engine got a damned good rinse inside. Even though we (obviously) only give our engines good quality full synthetic lubricants there are plenty places for bits of ick to end up after years of use. Not to where it is gross in the engine... but it is there. That ick is going to have gotten pressure washed via the crankshaft and reciprocating assembly making what looks to be a ball of taffy of oil as it spins at speed. It will have overwhelmed the crankcase ventilation system and dumped some oil into the intake manifold. Oil that is long gone on the first test drive after correcting the oil level. Any chance this is where elevated concentrations of metals and sand (casting sand..hmmm) came from? I'd bet on it.

I gently suggest an agreement between you and the shop owner that should anything unpleasant happen with the engine (oil related... leaks and crankcase ventilation up to lubrication related issues as this oopsie will have zero effect on anything related to cooling, electrical, fuel) in the next year or so he will take care of it. You speak of having had a good relationship with this repair shop until now. You sure 'One and done' is the right way to handle it? No doubt the shop owner does not want to lose you as a client. You didn't divorce her for an overcooked meal or not ironing your slacks just so.

Drive it and see how she does. My nickel in a bet says she is OK or at worst needs a PCV or oil seal repair.

 

All of this underfill and overfill is surprising given the degree to which inventory control is normally regulated to manage supplies and prevent employee theft. Parts and fluids should be accounted for and billed to each customer for the work that's completed. Even waste fluid needs to be accounted for so that it can be properly disposed of. When there are service techs screwing up, the tech supervisor is also at fault for not double checking all the paperwork. Complicated and time-consuming? Yes, but this is how quality control is managed by responsible shops, and given that all this normally takes is a barcode scan, inexcusable.

 

Considering how you feel about what happened and how serious the engine trouble could be, sticking with the same service provider might not be the best idea. Instead, I'd suggest finding a trustworthy independent mechanic who knows their stuff when it comes to your car's make and model. That way, you can feel more at ease knowing your engine check and any fixes will be handled professionally. Get ready for a thorough check-up and maybe even an engine rebuild. Keep talking openly with the service provider about what's going on and how much it might cost.

 

Inventory control? LOL.
At the dealership and most shops a work order is written. The oil change is entered into the computer as a 'labor op' that populates parts on the ticket with a labor description. Parts will pull the oil filter and drain plug gasket(s). It is not as though each individual quart of oil is scanned and handed out... in particular where the oil is purchased in bulk and is delivered via hoses right at the service bay as is the case in most repair shops. Smaller shops may hand out a pair of five liter jugs. Used oil is disposed of in the bulk container (we used a pair of 550 gallon containers) to be pumped out by the oil disposal company who doesn't charge by the gallon for that service. Employee theft? I encouraged my guys to change their oil with the synthetic oil on the rack when needed. Also to top up client cars that needed a quart any time needed. The whole world isn't out to get you! Really.

 

Glad to hear this shop seems to be stand up and have your back. Everyone makes mistakes and it seems like they owned it, and more importantly you are willing to continue giving them a chance. I'd imagine this will pan out in your favor long term in the future. It's hard to find accountability in the auto industry.

 

Thanks for the insight on how the real world works. Their auditors must love them.