Oh I didn't know the om642 was the diesel. Yeah that pcmo 20wt oil is too thin and isn't made to deal with diesel soot.
Hypothetical question with regard to incorrect oil use.
- Thread starter Tikka
- Start date
No idea. No gauge. Likely not very...NA.
edyvw
$50 site donor 2026
Personally, I would just change oil.
But you can't have a long and contentious thread if you do that.
Yes, that would make it easy. How much stress does one need when dealing with the service garage if the viscosity ends up being 20 grade via used oil analysis.
If you're talking about DIY, that's not an option for some people. The OP hasn't stated one way or the other if that's an option.
That is the best option, though.
Hi.
Thank you to everyone who has taken time to reply.
Firstly, as has been pointed out, the engine in my Jeep is the Mercedes OM642, V6 Diesel engine. It has no DPF. In 2008 they were not factory fitted. The manufacturer recommended oil is 5w-30 MB229.51/52. I have zero fuel dilution issues.
They assured me it was just an invoice mistake and correct grade and spec was used. They generally use Petronas fluids. They have said they will supply a corrected invoice.
Even if they had mistaken my Mercedes unit for the later WK2 Jeep with the Ecodiesel they would have used 5w-40.
Short of calling them a liar i am not sure what i can really do. The workshops are in a separate building to the service dept, no access allowed to public. If i demanded an oil change they could just lie and not do one.
In the past if they have made a mistake they have 'owned' it and corrected it.
I could get a used oil analysis done but it would be as cheap to vacuum the oil out and change.
My enquiry was born out of curiosity as to what would happen if a 0w-20 oil had been used in this engine. Timing chain issues? Turbo issues?
Many thanks.
Thank you to everyone who has taken time to reply.
Firstly, as has been pointed out, the engine in my Jeep is the Mercedes OM642, V6 Diesel engine. It has no DPF. In 2008 they were not factory fitted. The manufacturer recommended oil is 5w-30 MB229.51/52. I have zero fuel dilution issues.
They assured me it was just an invoice mistake and correct grade and spec was used. They generally use Petronas fluids. They have said they will supply a corrected invoice.
Even if they had mistaken my Mercedes unit for the later WK2 Jeep with the Ecodiesel they would have used 5w-40.
Short of calling them a liar i am not sure what i can really do. The workshops are in a separate building to the service dept, no access allowed to public. If i demanded an oil change they could just lie and not do one.
In the past if they have made a mistake they have 'owned' it and corrected it.
I could get a used oil analysis done but it would be as cheap to vacuum the oil out and change.
My enquiry was born out of curiosity as to what would happen if a 0w-20 oil had been used in this engine. Timing chain issues? Turbo issues?
Many thanks.
And this is why I change my own.Or, like my toyota dealer, they could put on the invoice that they changed the oil, then not change the oil at all. That was funny. Re-confirmed my distrust in dealers. I called them out on it obviosly, and of course they backpaddled and then said I wasn't at high enough miles to need a oil change. I asked why they put it on the invoice. I also pointed out that I was at 12 months - the Toyota specified interval (since they had changed it).
In the end the only way to 100% ensure its done right is to DIY.
edyvw
$50 site donor 2026
Nah, whatever he wants. DIY, or taking it to an indy to do it with proper oil. If someone put 0W20 in my Sequoia (which, by the way, is recommended for 0W20, but I don't use it), I would not lose sleep. But in that engine? It would be out in the next hour, and the dealership would never see me again. Google reviews would, on the other hand.
Peace of mind go elsewhere, your own money I know, and have a good oil put in. Think of it as a BITOG flush, free. Sort of.
Last edited:
4wd
$50 site donor 2026
You would not post here if paperwork fixes this …
Change the oil no matter who pays - Sleep matters!
This. Assurances mean nothing. If there's a failure, the only paper trail is the wrong oil going in.They assured you.
I wouldn’t feel assured at all. I would demand another service with the correct oil. They can’t argue too much, it’s right there in black and white. Keep a copy of the old invoice, and a copy of the new one stating what happened.
I sure wouldn’t waste my time and money on samples and analysis because they made a mistake in the shop or at the service desk. Why should that burden fall on you?
They need to change the oil (even it if IS the right stuff) and document correctly to give you what you actually paid for.
Shame on*mercedes* dealer for "meh, we think it's the right stuff, best of luck" instead of instantly recognizing the need to make it right by changing oil as soon as possible at no cost to you with apologies for the inconvenience.
Pretty sad that you can get such sloppy customer treatment even at a dealership selling some REALLY expensive vehicles. This is the same department that will stand behind a new $200k AMG S63?
Horrible. Do better, dealers of premium prestige products.
If I were in the OP's shoes, the oil would have to be changed for my peace of mind.
My day job is sales, I'm very aware that the bottom 10% of customers cause 90% of a company's headaches, and I apologize for the headache I'm going to cause, but today that headache is going to be me. It's probably just a paperwork glitch, but for my own peace of mind please change the oil again, and let me verify that the right oil is being put in my vehicle.
If they won't do that then I'd change the oil myself and they'd probably never see me again.
My day job is sales, I'm very aware that the bottom 10% of customers cause 90% of a company's headaches, and I apologize for the headache I'm going to cause, but today that headache is going to be me. It's probably just a paperwork glitch, but for my own peace of mind please change the oil again, and let me verify that the right oil is being put in my vehicle.
If they won't do that then I'd change the oil myself and they'd probably never see me again.
CleanSump
Site Donor 2026
With no DPF then mid/low SAPS isn't really lelevent. I would still want a minimum HTHS of 3.5 and Diesel dispersants oil. xW-20 won't get you there.
AZjeff
$50 Site Donor 2023
Same thing happened to me on the first free dealer oil change on a new truck. The invoice said 0w20 oil. The truck calls for 5W-30 oil. I asked the service writer if this was correct and he said absolutely if that's what it says. That's what we used and I said well you used the wrong oil. The service writer beside him jumped in and argued and said oh no, they just hit the wrong button when they made the invoice. I didn't demand they put in 5w-30 because who would you believe? Took it home and put the correct oil in and didn't bother with the 2nd free OC.
If that actually happened, your engine would probably be okay for a quick drive, but 0w-20 is way too thin for an OM642 long term. Those engines need the thicker 5w-30 stuff to protect the bearings and the turbo, especially when things get hot.
Running the thin oil could lead to extra wear or even timing chain issues over time. Since the dealer says it was just a typo, you're likely fine, but I'd definitely keep that invoice just in case something feels off later.
Running the thin oil could lead to extra wear or even timing chain issues over time. Since the dealer says it was just a typo, you're likely fine, but I'd definitely keep that invoice just in case something feels off later.
Buy a $5 syringe with a hose, get an oil sample and send it for $15-20 for oil analysis to sleep with pease of mind.
If it comes out 0W-20 bring it back to the dealer for another oil change or change it yourself and never go for an oil change at the dealer.
Similar threads
