Xundir

tl;dr
I've been quoted $42,000 for a brand new engine, and various other affected components, for my 2018 Mercedes C43 after experiencing some pretty bad engine rod knock and bringing it into the dealership for diagnosis. They found a large amount of bearing metal in the oil filter and have advised that the entire engine needs to be replaced. I get my car serviced at a non-Mercedes dealer, and am wondering what kind of recourse I have, if any, for getting my car fixed without having to shell out tens of thousands of dollars.

Background
I purchased the car at 38k miles, and have had zero mechanical issues throughout my 20,000 miles of ownership. I've only done two services on the car, one for the 50k interval back in August 2022, and another for the 60k interval in November 2023 before I put the car up for winter. Each of these intervals included an oil/filter change.
I've taken my sports cars to a used-car dealership that specializes in high-end vehicles that make my car look like chump change in comparison, solely because I thought I would get a similar level of service quality for a little bit less than taking it to a dedicated Mercedes dealership. At least so I thought.
Looking back at service records, it looks like my 50,000 oil change used 5W-30 oil, while the manual explicitly states that Mercedes AMG models should only use 5W-40. They used 5W-40 oil for my 60k maintenance. They also added a BG115 oil additive each time, while the manual explicitly states not to use any additives, as it could damage the engine. They used an aftermarket oil filter for each service. I'm not savvy enough with cars to know how impactful any of these are as far as what kind of damage they can potentially cause to an engine, especially on a high-performance sports car that occasionally gets driven quite hard (never taken to a track, just some spirited drives from time to time).

What Happened
Over the last couple of months, we've had a handful of warm days where I took the car out and everything was fine. Starting in April, I started sometimes picking up on a kind of "clicking" sound, that I didn't think much of since the car was driving fine, I didn't see any dash lights, and, well, I simply had no reason to suspect that anything wrong since I had just recently gotten the vehicle serviced and inspected. I thought it would work itself out. The noise originally was only present when the car was warm, and I only noticed it at low speeds in environments where the noise could bounce off of a wall back at me. Eventually the noise began to become more noticeable, and at that point, I swung into the non-Mercedes dealership to inquire about the noise. They said to come back next week and they would take a look at it. I did, and they were busy again, so I scheduled an actual appointment that was a couple of weeks out, and went about my day. As you might expect at this point, the noise has now grown to be a real problem. It's very clearly a knock, and I know something is wrong at this point. I call the Mercedes dealership that is 5 minutes from my house and schedule for an inspection for the noise, and that brings us to what you read in the tl;dr.

Seeking Advice
As alluded to in the title, I'm seeking advice for how I can/should proceed. I suspect negligence from the non-Mercedes dealership with regard to the services they performed on my car. I suspect that the work they did directly caused my engine to slowly degrade to the point that it now has to be fully replaced. None of the service advisors at my Mercedes dealer, in all of their combined years of service, have ever seen an engine failure like this on a car with this few miles.
I've reached out to the non-Mercedes dealer to let them know that I won't be able to bring the car in for my currently-scheduled appointment as the car is no longer able to be driven. I'll have to have it towed. They said they would give me a call back next week after they can free up some space in the lot, and want to have the car towed to take a look at it themselves. I asked who would be paying for this, and they're obviously not committing to taking any financial liability at this time, which is fair.

So what are my options? Should I let them take a look at the car? Is there anything I should ask from the Mercedes dealer who currently has possession of the car before I hand it over? Does insurance even cover situations like this? Is this a question for a lawyer? Am I simply screwed?

Hungalow

First thing I would do is go to the Mercedes dealership to determine the cause of the failure.Was it oil type???oil filter?? or or user issue. With the reaction they had for a blown engine with low kms kinda tells you whats up. Once you know that then you can go back to the non Mercedes dealer that you took the car to with proof of the cause. Of course the shop.will deny. You might have to get your lawyer involved.Of course it's not gonna be easy...You might wanna consider a used engine from a wrecker which can be had for less than 10k
edit: insurance wont be of any help unless you get it conveniently stolen...or fire...
Sorry bout your sit and good luck

user33

I'd tend to agree with Hungalow. For sure, I wouldn't take it to the indy shop until MBZ has been able to form an opinion about the cause for the failure (and exactly what did fail).

streborx

$42K is considerable cash to put into a 6 year old / 60K mile vehicle. What's the current KBB value? I'd sooner put $42K into a new set of wheels, and part out the C42.

wildta

The $42k has to be more than the blue book value that's for sure.

Xundir

$42k absolutely totals the car. KBB private party is about $34k-$37k for my spec.

If I get pinned with repairing this out of my own pocket, I'll probably end up selling it as-is to someone who is interested in rebuilding it, or repairing it with a used engine of similar mileage. Not even considering the $42k quote, it's just what MB provided since I asked them to do so.

Xundir

Anyone have any idea how many shop hours it would take to determine cause of failure? Just curious what I'm signing up for since their labor rates are quite high... Do they have to pull the engine, or would it be accessible from the underside? Or is it just impossible to know beforehand

Hungalow

Shouldnt take more than a few hours..its not like mbz has gotta dismantle engine...they should be able to tell from oil condition at present...metal filings in filter or wrong type filter....also if there was some kinda ecu or electronic failure there should be codes present in ecu. If the non mbz dealer screwed up with wrong oil and filter or quantity the bzn dealer should be able to determin that pretty easily. Once you got that in hand should be straight forward..

Xundir

Oh, they've already done all of this then. I had them diagnose the engine noise and their findings were that the oil filter and oil filter housing had a bunch of bearing metal present in each. My service logs from non-MB dealer indicate that they used 5W-30 for my 50,000 maintenance, and 5W-40 for my 60,000 maintenance. They also used a BG115 oil additive for each interval. The manual states that AMG models should only use 5W-40, and no additives, as they can lead to engine damage. They used an aftermarket oil filter for each interval as well.

I haven't had them run any diagnostics on the ECU. Didn't know that was a thing so I can circle up with my service advisor tomorrow and see if he knows anything about that.

Xundir

These are some of the images they provided me with during their inspection:

Hungalow

I think you got all you need to place blame on the non bnz dealer....hopefully the ecu has no stored codes to potentially let them off the hook.
It will not be easy to make them take responsibility and dish out money so be aggressive and dont give up.

This kinda reminds me of when I bought a brand new home years ago I noticed some issues..they tried to fluff me off...we couldnt agree so I made up a sign and picketed in front of sales office on the sidewalk of course..not their property. Stating " they got my cash I got their trash" I lasted 3 hours and got everything I wanted fixed and more...free kitchen backsplash..shower door....full wood floors upstairs also.

For you theres alot of money at stake so put your ducks in a row and see if you can resolve yourself if not get a lawyer involved...if and when you win they fix the car and pay your lawyer costs...
Good luck
btw where you located US?

Xundir

US, yep.

streborx

Seems as if the old oil was drained, the filter replaced and the engine was fired up to check for leaks before the new oil had been poured in.

TwoC400s

You're looking at the wrong oil qualities. Was the oil MB 229.5 certified? that's really all that matters, weight is irrelevant (your owner's manual can be superseded by newer tech documents at any time).

There's almost no way "oil type" or oil filter caused this unless you put actual track miles on the engine. You mentioned you put the car up for the winter, so unless you put 9K (hard) miles on the oil, put it up for the winter, and then immediately took it out of winter storage and flogged the ever-living snot out of it; this isn't an oil issue. Any MB 229.5 spec'd oil would've easily met all lubrication demands. I've personally put over a dozen 1/4 mile passes on Castrol Euro 5w30, driven it all winter, and then put 4 spring 1/4 mile passes on it before doing an oil change with zero issues.

Now, the oil additive COULD be an issue. It's obviously NOT MB 229.5 cert'd and doesn't belong in your car AT ALL.

Unlikely the filter had any play either unless it obviously failed (ie collapsed) which the MB dealership should have noticed.

TwoC400s

this is the nightmare scenario.

definitely possible, and no dealership would ever own up to it.

Xundir

I’m not sure what type of oil they used unfortunately. The service record only says viscosity. It sounds like the filter they used is from a reputable brand (Mann HU 7025 Z), so I’m sure that wasn’t a problem unless it was installed improperly. MB didn’t mention anything about that though when they inspected.

Just to clarify, I drove the car over the winter after 50k maintenance when the 5W-30 was used. The car never sat. I put maybe 150 miles on before garaging it from November to March after the 5W-40 was put in for the 60k maintenance. The car warmed up for about 25 minutes before I put it in drive in March. I have never once pushed the car hard before the transmission temp turns white on the AMG screen, which is always well after the oil temp warms up.

streborx

No matter where you have your oil changed, be assured the chore is being done by some minimum wage HS-dropout flunkie, who's likely smoking weed during breaktime and/or popping gummies on the job. I've been doing my own oil for 50 years (just did my 2 Jeeps this weekend), and always know the oil type/filter brand I used and that it's been done correctly.

You're right - nobody is going to own up to it, and even shredded crankshaft bearings won't incriminate anyone.