M112 V6 CLK 320 W209 oil weights according to MB
10-09-2019, 01:21 PM
#1
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Thread Starter
M112 V6 CLK 320 W209 oil weights according to MB
I'm posting some info about a very amusing empirical test with various "grades and weights" motor oils in a M112 engine. Hopefully help some people clarify some urban legends. It's a common topic to debate endlessly about "best" oil, "best" W and "best" viscosity.
So quick background:
The M112 V6 is a common engine for many benzes. It is neither very modern nor a vintage. Powerful and reliable but definitely not the sportiest engine out there. But then, it still gets your butt from 0 to 100km/h in less than 8 seconds and can safely cruise your passenger holding a glass of champagne at 200km/h at 4300rpm still having a conversation. In French we have a word for these large slightly lazy engines: un veau. A veal lol
A few weeks ago I came up with the question of oil grade for the next oil change of my 15y old/190'000km W209 CLK 320 (M112). Bevo indicates approvals 229.1/229.3/229.5 and anywhere from 0W30 to 10W60. I also noticed recently in shops the emergence of 0W20 oils (not rated for the M112) and wondered if it might make a positive difference in driving experience.
So far I have mostly used full synth 5W40 or 0W40, changing oil twice a year. Our winters in Switzerland aren't anymore as cold as before. We hardly reach water-freezing temperatures. As a consequence I never worry about the W rating. My own experience in the army is that by very low temps (I mean below -15°C/0°F), you have more problems with battery, door seals and grumpy crew than motor oil.
Recently, reaching 150'000km, I switched to semi-synth Total 7000 10W40 for it's higher wear-protection. I would use Mobil 1 FS but it's pricey here in Europe. Engine runs fine. No particular oil burn. But then again I don't really check. Oil warning has never come up. I remove filter, drain old oil, pour 8l and voilą.
Anyhow, a retired friend that owns a group of car dealerships laughed at me, suggested I should leave the M112 alone. It's not one of these modern micro-engines that require almost medical-grade fluids and weekly manucure
Anyhow, he told me that he would bet a finger that I, daily driver, would be incapable of observing a significant difference between grades. And offered a blind trial. He would fill the M112 without telling me what oil and let me drive a few days. And then change again. And again. And hear my feedbacks. He would also check compressions, change fiter and reset the transmission ECU at every change. First to establish a baseline, then to observe any changes (if any). First compressions test with used Total 7000 10W40 checked in the lower factory tolerance for a new engine. Not bad for a 190'000km engine.
So, to make it short 6 different oil weights from 0W20 to 10W60 were used. Both MB approved and not approved.
5W30 / 5W40 / 10W40 : no observable difference as a driver. No measurable differences in compressions. All MB-approved.
0W30, MB approved: slightly softer cold starts. No particular difference in driving experience. No significant difference in compressions.
0W20, MB approved but not for the M112: definitely swifter cold starts. More energetic accelerations in city driving (engine revs up a tad faster). Slightly less pressure needed on the gas pedal to keep up with city traffic. Slightly less engine-braking requiring more frequent use of brakes. An odd japanese-engine feeling without the 10'000rpm noise lol No notable difference in motorway driving except the reduced engine braking requiring to closely watch the distances. Compressions just a tad lower than baseline but not dramatic.
10W60, not MB approved (could not find the MB approved Mobil 1 FS X3 so Ravenol RSS was used). The most notable observations are compressions back to the higher of factory figures for new engines, a bit stronger motorway accelerations, the relative feeling of a bigger engine, quieter engine (less rumble and mumble).
Discussion:
As a driver, I felt a difference only with the super thin 0W20 and the heavier 10W60. All other are indistinguishable. My buddy explained this by the significant difference in viscosity of the two extremes. The super-thin 0W20 is much thinner and offers less resistance hence less friction, less loss of power and more nimble feeling. Indeed that can be felt with the large M112. Note that similar "benefit" could be obtained with smaller diameter wheels. As for the 10W60, the much higher viscosity makes up for the wear of older cylinders, increases compressions and ultimately the power transmitted to the wheels. A clear benefit in long distance touring. Two different contexts. I drive mostly in city. With occasional holiday touring across Europe. Should I use either of the extremes? Technically, my buddy could not strongly advise one or another of the 6 as "better". Just that he personally would feel unconfortable taking the M112 on a long distance tour with the super-thin 0W20 designed for newer hybrid smaller engines. Also, using a reputable non-MB approved oil won't automatically destroy my M112. Some oils are specifically formulated for the shortcomings of engines that have notoriously hard time complying with stringent emission levels (follow my gaze lol). These oils won't make the M112 any cleaner. Nor damage it. You simply won't reap the additional benefits you paid for. Only unknown part is the effect on the long term on old seals and gaskets. My buddy even suggested that, given the ease of replacing oil in the M112 engine, I could buy a sucker, use 0W20 for my city driving, and switch to 10W50/60 when I decide to cruise through South of France or Tuscany. Or simplify my life, use the Mobil 1 FS 0W40 or the much cheaper Total 7000 10W40 or any similar and simply forget about it. Again, it's not one of these modern engines that require almost medical-grade fluids.
All in all this was an enlightning and quite amusing experience. Will I use the 0W20 to optimize city driving? I'm tempted. Especially if it comes with a significantly better mileage. But I'm slightly worried about the old seals. There are no leaks and I really don't want to start fiddling with seals. On the other hand, having a nimbler CLK (relatively, it's no Mini Cooper) might encourage me to use the accelerator more often, negating any benefit in mileage. I think I might go for the 10W60 designed for mature engines. Slight improvement in city mileage won't buy me a dinner. But keeping my engine reliable will definitely allow me to take my gf for an impromptu weekend in Monaco or Milano.
What are your thoughts? Have you experienced with different oils? Any funny adventures? Notable changes?
So quick background:
The M112 V6 is a common engine for many benzes. It is neither very modern nor a vintage. Powerful and reliable but definitely not the sportiest engine out there. But then, it still gets your butt from 0 to 100km/h in less than 8 seconds and can safely cruise your passenger holding a glass of champagne at 200km/h at 4300rpm still having a conversation. In French we have a word for these large slightly lazy engines: un veau. A veal lol
A few weeks ago I came up with the question of oil grade for the next oil change of my 15y old/190'000km W209 CLK 320 (M112). Bevo indicates approvals 229.1/229.3/229.5 and anywhere from 0W30 to 10W60. I also noticed recently in shops the emergence of 0W20 oils (not rated for the M112) and wondered if it might make a positive difference in driving experience.
So far I have mostly used full synth 5W40 or 0W40, changing oil twice a year. Our winters in Switzerland aren't anymore as cold as before. We hardly reach water-freezing temperatures. As a consequence I never worry about the W rating. My own experience in the army is that by very low temps (I mean below -15°C/0°F), you have more problems with battery, door seals and grumpy crew than motor oil.
Recently, reaching 150'000km, I switched to semi-synth Total 7000 10W40 for it's higher wear-protection. I would use Mobil 1 FS but it's pricey here in Europe. Engine runs fine. No particular oil burn. But then again I don't really check. Oil warning has never come up. I remove filter, drain old oil, pour 8l and voilą.
Anyhow, a retired friend that owns a group of car dealerships laughed at me, suggested I should leave the M112 alone. It's not one of these modern micro-engines that require almost medical-grade fluids and weekly manucure
Anyhow, he told me that he would bet a finger that I, daily driver, would be incapable of observing a significant difference between grades. And offered a blind trial. He would fill the M112 without telling me what oil and let me drive a few days. And then change again. And again. And hear my feedbacks. He would also check compressions, change fiter and reset the transmission ECU at every change. First to establish a baseline, then to observe any changes (if any). First compressions test with used Total 7000 10W40 checked in the lower factory tolerance for a new engine. Not bad for a 190'000km engine.So, to make it short 6 different oil weights from 0W20 to 10W60 were used. Both MB approved and not approved.
5W30 / 5W40 / 10W40 : no observable difference as a driver. No measurable differences in compressions. All MB-approved.
0W30, MB approved: slightly softer cold starts. No particular difference in driving experience. No significant difference in compressions.
0W20, MB approved but not for the M112: definitely swifter cold starts. More energetic accelerations in city driving (engine revs up a tad faster). Slightly less pressure needed on the gas pedal to keep up with city traffic. Slightly less engine-braking requiring more frequent use of brakes. An odd japanese-engine feeling without the 10'000rpm noise lol No notable difference in motorway driving except the reduced engine braking requiring to closely watch the distances. Compressions just a tad lower than baseline but not dramatic.
10W60, not MB approved (could not find the MB approved Mobil 1 FS X3 so Ravenol RSS was used). The most notable observations are compressions back to the higher of factory figures for new engines, a bit stronger motorway accelerations, the relative feeling of a bigger engine, quieter engine (less rumble and mumble).
Discussion:
As a driver, I felt a difference only with the super thin 0W20 and the heavier 10W60. All other are indistinguishable. My buddy explained this by the significant difference in viscosity of the two extremes. The super-thin 0W20 is much thinner and offers less resistance hence less friction, less loss of power and more nimble feeling. Indeed that can be felt with the large M112. Note that similar "benefit" could be obtained with smaller diameter wheels. As for the 10W60, the much higher viscosity makes up for the wear of older cylinders, increases compressions and ultimately the power transmitted to the wheels. A clear benefit in long distance touring. Two different contexts. I drive mostly in city. With occasional holiday touring across Europe. Should I use either of the extremes? Technically, my buddy could not strongly advise one or another of the 6 as "better". Just that he personally would feel unconfortable taking the M112 on a long distance tour with the super-thin 0W20 designed for newer hybrid smaller engines. Also, using a reputable non-MB approved oil won't automatically destroy my M112. Some oils are specifically formulated for the shortcomings of engines that have notoriously hard time complying with stringent emission levels (follow my gaze lol). These oils won't make the M112 any cleaner. Nor damage it. You simply won't reap the additional benefits you paid for. Only unknown part is the effect on the long term on old seals and gaskets. My buddy even suggested that, given the ease of replacing oil in the M112 engine, I could buy a sucker, use 0W20 for my city driving, and switch to 10W50/60 when I decide to cruise through South of France or Tuscany. Or simplify my life, use the Mobil 1 FS 0W40 or the much cheaper Total 7000 10W40 or any similar and simply forget about it. Again, it's not one of these modern engines that require almost medical-grade fluids.
All in all this was an enlightning and quite amusing experience. Will I use the 0W20 to optimize city driving? I'm tempted. Especially if it comes with a significantly better mileage. But I'm slightly worried about the old seals. There are no leaks and I really don't want to start fiddling with seals. On the other hand, having a nimbler CLK (relatively, it's no Mini Cooper) might encourage me to use the accelerator more often, negating any benefit in mileage. I think I might go for the 10W60 designed for mature engines. Slight improvement in city mileage won't buy me a dinner. But keeping my engine reliable will definitely allow me to take my gf for an impromptu weekend in Monaco or Milano.
What are your thoughts? Have you experienced with different oils? Any funny adventures? Notable changes?
Last edited by SwissKiss; 10-13-2019 at 06:13 AM.
