Oil for MB with *warm* start knock issue

Messages
237
Location
AZ
60.000 miles and it knocks. Yep, German cars are great. I would add something like Cerrocoat or some other slippery stuff to help keep it going.
Good luck.
 
Messages
11,168
Location
MA
60.000 miles and it knocks. Yep, German cars are great. I would add something like Cerrocoat or some other slippery stuff to help keep it going.
Good luck.
The M273 engine isn't that common, they didn't sell that many of them although it was basically just the V8 version of the V6 engine which was much more common. With that said, this is not a common problem, haven't really heard much mention of this in the E class forums. It's probably why you see more mention of it in the C class forums, they sold a lot more of those and those reference the M272 engine.
 
Messages
4
Location
SoCal
I didn’t know it was a common issue. My car, 08 E350 with a M272 has the same issue, though I am at a tad over 180k miles. I’ve had it for about a year now and thought that it was lifter noise or that it was just me hearing things. The owner before me used Motul 15W-50 for at least 3 oil changes as recommended by the shop he serviced it at and the first thing I did was to put Mobil 0W-40 in it. I change it every 7500 miles because the OCI in the car is set for 15000 for whatever reason. Since I though it was lifter noise I purchased Liqui Moly Leichtlauf High Tech 5W-40 to give it a try but looking at VOAs it doesn’t seem like the best thing to do. Any suggestions?
 
Messages
18,142
Location
Upper Midwest
I didn’t know it was a common issue. My car, 08 E350 with a M272 has the same issue, though I am at a tad over 180k miles. I’ve had it for about a year now and thought that it was lifter noise or that it was just me hearing things. The owner before me used Motul 15W-50 for at least 3 oil changes as recommended by the shop he serviced it at and the first thing I did was to put Mobil 0W-40 in it. I change it every 7500 miles because the OCI in the car is set for 15000 for whatever reason. Since I though it was lifter noise I purchased Liqui Moly Leichtlauf High Tech 5W-40 to give it a try but looking at VOAs it doesn’t seem like the best thing to do. Any suggestions?
What in the VOA exactly do you see that makes it not "the best thing to do"?
 
Messages
4
Location
SoCal
The lack of molybdenum in it. I will be testing it out anyways though since I have already purchased it. Maybe I’ll be proven wrong. I am in no regard an expert in the field.
 
Messages
18,142
Location
Upper Midwest
The lack of molybdenum in it. I will be testing it out anyways though since I have already purchased it. Maybe I’ll be proven wrong. I am in no regard an expert in the field.
Ahh I see. You question the ability of Liqui Moly to properly formulate an oil to achieve Mercedes-Benz 229.5 approval.

How are you planning on testing it to see if it doesn’t meet the approval requirements?
 
Messages
4
Location
SoCal
I am sure they can make good oil, I am not questioning their abilities. By testing it I meant I will be putting it in the car and observing.
 
Messages
496
Price always go down over time but I suppose it will reach a point where they will start to go up again. Plus all it takes is one idiot on the road to smash your ride. Probably premature to buy an engine although I suppose you could always turn it into a table stand.
Yes, its all fun and games until somebody hits your beloved car, I still miss my 2.5 SEL Jetta!

I had just replaced the ATF too! The expensive ravenol stuff too!
 
Messages
184
Location
WI
I had an '08 C300 (6 spd manual!) for a few years that exhibited this low-end knock on warm startup, just a second or so. I had read plenty of other stories on the MB forums where I'm still a member and came to the conclusion that it was not very common, but neither was it detrimental.

As overkill summarized it earlier, MB had been made aware of this issue to the point where they replaced main bearings in some cars. For a few owners, that solved the issue but for many others it didn't. I think MB ended up throwing their hands in the air and concluding "it's normal."

Most of those folks either sold or traded those M276-engined cars long before any failures ever happened, but the noise was keeping them up at night (probably because of forums like these).

I would experiment with different 229.5 spec motor oils and see how the noise is. Ideally there shouldn't be much difference across brands that are approved for a given spec, but we know oil mfrs blend oils differently to achieve a given spec.
 
Messages
4
Location
SoCal
That's what I was planning on doing. Just wasn't sure what to try after the Liqui Moly Leichtlauf High Tech 5W-40. I was thinking either 5W-40 Formula M or the Castrol 0W-40 that can be obtained from Walmart.
 
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