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Got my results back from my most recent round of testing. Could someone possibly try to explain this in terms a layman might understand?
Any ideas what's causing the fuel dilution? For context, the first test was when i had the EC tune on it, before its first service during my ownership. Second analysis is with a ln Evotech tune and after a service at the dealership
How many miles on the car and have your injectors ever been changed? They tend to leak (which can explain the increasing level of fuel dilution) and are a recommended 50K mile maintenance item on M156s.
Lastly, 15W40? That's a risky weight for an M156 in a very hot climate and a downright dangerous one for cold weather.
Really hoping that the 15w-40 is a typo and supposed to be 5w-40. If you're really running 15w-40 that needs to change.
It is definitely 5w40, its a typo on their end. Good pickup everyone.
As for fuel dilution, I have heard some tuners say that its normal to run extra fuel in tuned vehicles to cool the cylinders down and as a safety precaution, and that at high revs a little may escape into the sump. Apparently it's "fine" and won't make my engine go pop. At the next service i am debating on having the injectors replaced, as they are still the originals from factory, or having them cleaned and flow tested as an added precaution.
Really hoping that the 15w-40 is a typo and supposed to be 5w-40. If you're really running 15w-40 that needs to change.
Originally Posted by Diabolis
How many km's are on that oil? The TBN would suggest you should change the oil more often.
I had it serviced at the dealership a few months ago, oil has maybe a few thousand ks on it. Service menu says its due for another service in like ~115 days. I change my oil probs every 5,000ks, depending on use. I wouldn't be surprised if the dealership didn't change my oil, and charged me if they have. *******s cracked my engine cover and did a bad job fixing it with sikaflex
W204 C63 Coupe, W166 ML350 BlueTEC, 928GT, C5 Z06 & IS300 race cars, EQE 4Matic+ on order
These days oil analysis labs don't check the TAN (Total Acid Number) when they do a UOA, but is has been repeatedly shown that the TAN rapidly begins to increase when the TBN drops down to 50% of what it is in the fresh oil. I don't know which Fuchs oil you were using, but pretty much any oil these days would start with a TBN of over 10 (M1 0W-40 has a TBN of 12.6 for example; the Rotella T6 - an unapproved HDEO oil - has a TBN around 10.6). Your samples show a TBN of 4.3 and 3.7, which means that the oil additive package was completely spent and that there was too much acid in your crankcase. If you're changing it every ~5K km, I suspect that you mostly drive short distances where the oil doesn't fully warm up and/or stay hot long enough for the moisture to evaporate. so you definitely need to change the oil more often.
These days oil analysis labs don't check the TAN (Total Acid Number) when they do a UOA, but is has been repeatedly shown that the TAN rapidly begins to increase when the TBN drops down to 50% of what it is in the fresh oil. I don't know which Fuchs oil you were using, but pretty much any oil these days would start with a TBN of over 10 (M1 0W-40 has a TBN of 12.6 for example; the Rotella T6 - an unapproved HDEO oil - has a TBN around 10.6). Your samples show a TBN of 4.3 and 3.7, which means that the oil additive package was completely spent and that there was too much acid in your crankcase. If you're changing it every ~5K km, I suspect that you mostly drive short distances where the oil doesn't fully warm up and/or stay hot long enough for the moisture to evaporate. so you definitely need to change the oil more often.
Thank you for the very clear and concise answer. I'll get an oil change sorted ASAP. I have never taken my car to the dealer before this instance, always used reputable indies and either supplied my own oil(penrite) or had them use an approved MB oil. This is the first time that I know of that my car has had fuchs in it. Is there a better brand i should be using to suit my applications? I.e liqui moly, shell etc? Or is 5w40 the same across the board?
I plan on dosing with ceratec, would this still be a good idea?
Fuel dilution is a calculation based on the viscosity of the oil weight you provide. Make sure you report the correct weight to the lab. Fuel lowers oil viscosity. I would give them a call and have them recalculate fuel dilution for 5w40 oil not 15w40.
W204 C63 Coupe, W166 ML350 BlueTEC, 928GT, C5 Z06 & IS300 race cars, EQE 4Matic+ on order
Originally Posted by Panzerbiscuit
Thank you for the very clear and concise answer. I'll get an oil change sorted ASAP. I have never taken my car to the dealer before this instance, always used reputable indies and either supplied my own oil(penrite) or had them use an approved MB oil. This is the first time that I know of that my car has had fuchs in it. Is there a better brand i should be using to suit my applications? I.e liqui moly, shell etc? Or is 5w40 the same across the board?
I plan on dosing with ceratec, would this still be a good idea?
While there are differences between various oils, the impact of said differences on a street driven car with an unmodified engine are fairly minimal (negligible may be a better word) if you stick with any MB 229.5 approved oil. Changing it often enough so that the oil additive package is not getting depleted (as was the case here) is by far the best thing you can do for the engine and far more important than the oil brand. If you are tracking the car then there may be other things to take into account, but they are pretty much immaterial if you're simply using the car as a daily driver.
While I personally don't subscribe to the notion that aftermarket oil additives are needed if you pick the right oil for the specific application and frequently change it, there are members here that do (or have in the past) so perhaps one of them can chime in. Keep in mind that even additives like Ceratec that may possibly work in reducing internal friction and wear and don't cause other problems (as there certainly are some that do) are not going to help with your issue here, namely the used up and diluted oil that is unable to provide the engine with optimal protection.
While there are differences between various oils, the impact of said differences on a street driven car with an unmodified engine are fairly minimal (negligible may be a better word) if you stick with any MB 229.5 approved oil. Changing it often enough so that the oil additive package is not getting depleted (as was the case here) is by far the best thing you can do for the engine and far more important than the oil brand. If you are tracking the car then there may be other things to take into account, but they are pretty much immaterial if you're simply using the car as a daily driver.
While I personally don't subscribe to the notion that aftermarket oil additives are needed if you pick the right oil for the specific application and frequently change it, there are members here that do (or have in the past) so perhaps one of them can chime in. Keep in mind that even additives like Ceratec that may possibly work in reducing internal friction and wear and don't cause other problems (as there certainly are some that do) are not going to help with your issue here, namely the used up and diluted oil that is unable to provide the engine with optimal protection.
Of course I'll change the oil prior to using any additives. It seems strange to me that oil that was recently changed is already past its use by date. Is it possible that the dealership never changed my oil? As it was fairly dark when i drained it. Is there anything in the results that could indicate this?
Very interesting discussion. I use ceratec but my personal clause was to only use it knowing that the environment is consistent and stable. With the acid base discussion I’m sure the detergents have a buffer zone but going past this buffer zone will cause a steep exponential increase in neutralizing power of the acid so there’s direct correlation with TBN. I am aiming to set up a 5k km oil change interval to net me the most consistent results. I wouldn’t recommend additives until everything else has been resolved. There’s too much mixing of solute/solvent going on and with foreign contamination (vapour) you’re results could get you unfavourable outcomes. I too suspect there is moisture and in chemistry water can be either basic or acidic depending on circumstance that can compound any closed environment (engine).
Very interesting discussion. I use ceratec but my personal clause was to only use it knowing that the environment is consistent and stable. With the acid base discussion I’m sure the detergents have a buffer zone but going past this buffer zone will cause a steep exponential increase in neutralizing power of the acid so there’s direct correlation with TBN. I am aiming to set up a 5k km oil change interval to net me the most consistent results. I wouldn’t recommend additives until everything else has been resolved. There’s too much mixing of solute/solvent going on and with foreign contamination (vapour) you’re results could get you unfavourable outcomes. I too suspect there is moisture and in chemistry water can be either basic or acidic depending on circumstance that can compound any closed environment (engine).
Cheers man,
I'll definitely try and sort the issues and fix the root cause of the low TBN before using any additives.
Im back in town and my oil has done 4,457kms since it's last change. It boggles my mind that my oil could have deteriorated to such a point over so few kms. I'm going to have the oil changed ASAP, and new injectors installed.
Update*
Car had an oil change this morning at the dude I usually use. Can't find any Liqui Moly 5w40 anywhere in Australia. Only supplier for Supercheap Auto in WA has dropped the contract, a number of other auto stores don't stock it, or their suppliers don't stock it anymore due to it being "obsolete".
Just used a Penrite HPR 5w40 for the moment until I find an alternative/buy some liqui moly online.
Mechanic reckons that the dealership basically has a fleet spec oil that they chuck in every vehicle, which is why it deteriorated so quickly. Will test the oil again after the same amount of time/kms and see what the results are like.
Update*
Car had an oil change this morning at the dude I usually use. Can't find any Liqui Moly 5w40 anywhere in Australia. Only supplier for Supercheap Auto in WA has dropped the contract, a number of other auto stores don't stock it, or their suppliers don't stock it anymore due to it being "obsolete".
Just used a Penrite HPR 5w40 for the moment until I find an alternative/buy some liqui moly online.
Mechanic reckons that the dealership basically has a fleet spec oil that they chuck in every vehicle, which is why it deteriorated so quickly. Will test the oil again after the same amount of time/kms and see what the results are like.
10-12-2020, 04:32 AM
