absurd oil consumption- turbo seal?
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Joined: May 2020
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From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
absurd oil consumption- turbo seal?
My CL65 begs me for a liter of oil every 80-140 miles lately, used to be more like 1200+ miles. Does this sound like a turbo oil seal? There are no leaks if I leave it idling for 10 minutes (underbody trays off), though the bellhousing seems pretty wet with oil on one side. Once every 25+ startups, I do notice a quick puff of white smoke... Some smoke as well if I'm really punishing it, but I figured that was just fuel. Went ahead and replaced the oil separator to see if that makes a difference.
I don't really feel like dropping the engine... I can, but I don't wanna. 118k miles on the odometer.
I don't really feel like dropping the engine... I can, but I don't wanna. 118k miles on the odometer.
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Joined: May 2020
Posts: 247
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From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
Crossing my fingers. Changed oil, replaced oil filler cap after noticing it puked oil at one point. Theorizing on PCV system being neutered by lack of crankcase vacuum/seal.
Anyways, HUUUUGE plume of oil smoke on startup after the change, went away after 30-60 seconds.
3/4 through a new tank of gas, and no requests to add a liter of oil yet.... Negative PCV/crankcase pressure might supplement turbo seal function? Could explain some things, given much more reasonable consumption the previous several thousand miles of operation.
I'll update as time drags on.
Anyways, HUUUUGE plume of oil smoke on startup after the change, went away after 30-60 seconds.
3/4 through a new tank of gas, and no requests to add a liter of oil yet.... Negative PCV/crankcase pressure might supplement turbo seal function? Could explain some things, given much more reasonable consumption the previous several thousand miles of operation.
I'll update as time drags on.
Last edited by JustTXn; Jun 11, 2025 at 10:50 PM.
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From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
I've lost my physical dipstick, but I had to replace the oil sensor several months ago, as it was faulty... Still may not be accurate, but so it goes. I've fed the car probably 10-15L of oil.
Anywho, I canged the oil fill cap and managed to go about 950 miles before the car asked for another quart of oil. I may have over (or under) filled the system (oil change), at about 10.3 Liters, but 950 miles is still a drastic change.
Only change is replacing the oil separator and oil filler cap, which did have a leak.
I'm assuming at this point it was a PCV system issue!
Anywho, I canged the oil fill cap and managed to go about 950 miles before the car asked for another quart of oil. I may have over (or under) filled the system (oil change), at about 10.3 Liters, but 950 miles is still a drastic change.
Only change is replacing the oil separator and oil filler cap, which did have a leak.
I'm assuming at this point it was a PCV system issue!
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2006 S65 AMG
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From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
Also, I've replaced the other PCV tube, the one that goes from the oil separator to the intake plenum on top of the engine (which has a check valve that was probably 20 years old).
Last edited by JustTXn; Jul 28, 2025 at 01:17 PM.
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From: Phoenix
222 S-65
OP.... How often does your engine get wide open throttle?
This is needed to keep the piston rings moving and making a good seal between piston and cylinder wall. Driving it gently makes for excess blow-by and excessive oil consumption. It may take a while. My 221 S-65 when I purchased it consumed quite a lot of oil. Over a year of hammering on it and oil consumption dropped to a liter every 3000 miles or so. Car was originally purchased by Canadian Government for high profile transportation. Prolly only got a boot of throttle just very briefly in a parking garage with no passengers prior to my time with it.
This is needed to keep the piston rings moving and making a good seal between piston and cylinder wall. Driving it gently makes for excess blow-by and excessive oil consumption. It may take a while. My 221 S-65 when I purchased it consumed quite a lot of oil. Over a year of hammering on it and oil consumption dropped to a liter every 3000 miles or so. Car was originally purchased by Canadian Government for high profile transportation. Prolly only got a boot of throttle just very briefly in a parking garage with no passengers prior to my time with it.
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From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
Hey John,
Extremely often
If I'm on a freeway I hit interesting speeds more often than not, and traction control stays off. I think I've put about 8500 miles on it so far... We'll see what happens. Oil consumption on this car increased suddenly and drastically, which is why I'm thinking something has changed.
The grommet that seals the bottom of the oil filler to the engine block looks like it was put in by a two year old, more out than in... so that may be another vacuum leak. No luck properly seating it so far.
Extremely often
If I'm on a freeway I hit interesting speeds more often than not, and traction control stays off. I think I've put about 8500 miles on it so far... We'll see what happens. Oil consumption on this car increased suddenly and drastically, which is why I'm thinking something has changed.
The grommet that seals the bottom of the oil filler to the engine block looks like it was put in by a two year old, more out than in... so that may be another vacuum leak. No luck properly seating it so far.
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2017 GLE350 4MATIC
Hey John,
Extremely often
If I'm on a freeway I hit interesting speeds more often than not, and traction control stays off. I think I've put about 8500 miles on it so far... We'll see what happens. Oil consumption on this car increased suddenly and drastically, which is why I'm thinking something has changed.
The grommet that seals the bottom of the oil filler to the engine block looks like it was put in by a two year old, more out than in... so that may be another vacuum leak. No luck properly seating it so far.
Extremely often
If I'm on a freeway I hit interesting speeds more often than not, and traction control stays off. I think I've put about 8500 miles on it so far... We'll see what happens. Oil consumption on this car increased suddenly and drastically, which is why I'm thinking something has changed.
The grommet that seals the bottom of the oil filler to the engine block looks like it was put in by a two year old, more out than in... so that may be another vacuum leak. No luck properly seating it so far.
In other words you are doing nothing. In your own words you have a “don’t wanna” perspective.
Bellhousing “pretty wet” is not normal and indicates significant oil leak. You are ignoring the obvious.
You need to aggressively diagnose, then aggressively replace parts based on diagnosis. This assumes you want to keep the car in the best condition possible for as long as possible and that you have the wallet to do it. Is this what you want?
Or dump the car. It’s an old MB V12. Is this what you want?
Last edited by chassis; Aug 27, 2025 at 08:42 AM.
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From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
You are theorizing, crossing your fingers and assuming.
In other words you are doing nothing. In your own words you have a “don’t wanna” perspective.
Bellhousing “pretty wet” is not normal and indicates significant oil leak. You are ignoring the obvious.
You need to aggressively diagnose, then aggressively replace parts based on diagnosis. This assumes you want to keep the car in the best condition possible for as long as possible and that you have the wallet to do it. Is this what you want?
Or dump the car. It’s an old MB V12. Is this what you want?
In other words you are doing nothing. In your own words you have a “don’t wanna” perspective.
Bellhousing “pretty wet” is not normal and indicates significant oil leak. You are ignoring the obvious.
You need to aggressively diagnose, then aggressively replace parts based on diagnosis. This assumes you want to keep the car in the best condition possible for as long as possible and that you have the wallet to do it. Is this what you want?
Or dump the car. It’s an old MB V12. Is this what you want?
Unfortunately I have a job, multiple hobbies, and limited stamina, so I'm unable to follow your creed of "fix everything all at once". It's been a problem-riddled sub-$20k car on a platform I'm largely familiar with, and as long as it leaks oil, it has oil, lol. I rank-order repairs by their importance to me and work through them. You may be terrified to discover I fixed the A/C before the right coilpack, and that I might fix the engine mounts before I fix the oil leak.
Keeping the same oil in the car longer doesn't affect the longevity of the drivetrain if I keep adding new oil to it
I've fixed the ABC system, ignition system, hydraulic trunk system, radio/comand system, sunroof, and keyless go so far, so I'll get around to the oil eventually. Probably when a free spot at the lift opens up. Or when I feel like it.... It's a cool 20 year old car, not a child with asthma. It'll survive.
==================================
An update though: The grommet that seals the oil check tube into the engine has all but disintegrated it seems- Crank-case vacuum is no longer present when removing the oil fill cap. This makes sense, and explains the oil consumption leaping back up to a liter every 100~140 miles. I've also found the oil return feed from the right turbo is largely crushed, I'd guess 85% of the original volume of the tube has been restricted... I'm assuming the engine has been out of this car at some point. Time to attempt to find the part number. MB's site has become trash diagram-wise.
Also Vinewanderer, good to know!
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From: Phoenix
222 S-65
OP worth doing is pulling the crankcase ventilation guy that lives on the front of the driver's side cylinder head. Have a look at the diaphragm inside of it. Nickel in a bet says that diaphragm is junk. Comes as an assembly from MB with the crankcase vent hose that goes to the left air filter housing. Easy replacement.
