S350 bluefficiency burning oil

[markheaney2]

Good afternoon, I have a s350 bluefficiency 2010 with 125000 miles on, about 6 months ago it started burning oil, it burns a lot more on a long run rather than doing the same amount of miles locally, it is now burning 3 litres per 1500 miles, there are no signs of blue smoke etc, the car runs perfectly although it only does 36 miles to a gallon a long run, no misfire etc, in all other respects it runs absolutely fine, pulls like a train, I have never had a mercedes that burns oil and I have run them for 30 years, any help would be appreciated.

 

[Robbo Cop]

Do you possibly have an oil leak? Can be hard to spot as sometimes leaking oil (or other fluids) can accumulate in the under trays leaving very little sign of any issues.

Hope this helps,

Rob ...

 

[markheaney2]

No oil leaks it is bone dry

 

[ernie]

The various elements that treat the exhaust (like the Cat Converter, etc.) are probably masking the blue smoke! I don't know the specifics of this engine, but turbo seals might be a possibility and worth investigating. Another might be a blocked crank-case breather, allowing oil fumes to be injested. I would be most worried about turbo seals because if they let go and the engine goes into 'runaway' mode, you're looking at a new engine at the very least. It really needs someone who knows these engines to check it out, but apart from general engine wear, I'd be worried about the turbo seals. Do you know the history of this car? I'm also wondering if there is something murky in its past! Or is it something that's developed over time?

Let us know what happens!

Ernie

Edit: Sorry just noticed that this developed 6 months ago!

 

[Jackcramerr]

What were your emissions on your last mot?
No smoke could mean its is pistion rings or oil scrapers of pistons. Thus letting the oil pass and burn in chamber.
Is there any sign of lag ? I.e when you acclerate, at low rpm there is low power but soon as ut revvs up it suddenly unleashes power?

 

[markheaney2]

On the last mot it passed on its first rev, as for lag it has always had a lag I would call it a flat spot low revs are fine it is after 2000 revs a one to 3 second delay, I have owned it about a year, I have fitted a new crankcase breather after reading that these can block up, the problem I have is a really good independent has had a look at it and it is the first v6 they have seen that drinks oil, the turbo looks quite new they have said, as from now if I want to go further it will cost lots of money in investigations, rings, pistons, turbo etc, I am at a loss what to do, I have an early s320 cdi that runs with more power 10 more miles per gallon same v6 engine the problem is the Dar has 45,000 pounds of extras, in every other respect it is immaculate and looks amazing, for that reason I would love to keep it..

 

[GordonTarling]

It surely wouldn't cost too much to have a good indi do a compression test - that ought to shed some light on things. "Turbo looks quite new" - I don't think you can accurately determine the condition of any engine part purely on how it looks. Find another indi who will look into it properly.

 

[kid-jensen]

The oil consumption on long journeys (implying that it's worse when the engine's hot) and performance issues do point to ring wear, but I would have expected blue smoke on acceleration. There's only so much that the Cat will mask but I would expect the DPF to be working much harder than it was designed to. This will almost certainly come back to bite you in the bum when it fails, and in the mean time it would be doing way more regens than normal to try to clear the excessive soot produced by the high oil consumption.
Sad to say that it sounds like serious money needs to be spent, so you have the option of spending that money, which I would understand if you didn't like that idea, or looking for ways of moving forward at lower cost.
This seems to offer two options: 1. Use thicker oil, or 2. Get a new name in the Log-book.

 

[markheaney2]

I think you may be right about the regeneration it seems to do too many even though this car does mainly long runs from york to london, I think I may have to bite the bullet and buy a new shape s class 2014 2015 because our council now insist on Euro 6 only on New chauffeur cars going on. Thanks for all your help everyone.

 

[Jackcramerr]

Stick with petrol hyrbid. Diesel is past.

Your emissions will go up as cat converter or dpf clogs up and fails to work. No smoke means it is burning it and getting past oil scrappers. Rings might be ok. This explains why you do not feel power loss but you know there is a lag. Theory is, oil goes past the scrappers but the compression is good. Thus you get lots of power at high rpm as it burns oil with fuel. Even though to prove this you need to do compression test. Not sure how it is done on diesel but petrol is easy.
Thicker oil will not help. Nothing will.
The best you can do is make sure you have the correct spec oil.
I have been through this road. You can start using cheaper but to spec oil and live with it till it fails mot on emissions. Or bin the car. Do not spend anything in it from now on. Just my opinion

 

[markheaney2]

I have decided to run the car for another 6 months and put up with the oil usage and during this time look for a Euro 6 s class, I am led to believe 2010 onwards bluetec s350 are all Euro 6 emmisions.