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What is your point? Design and manufacturing issue? Driver issue ("heavy throttle/engine lugging/infrequent trips etc") or what.

I think you need to give more background and clarity to exactly what you are trying to say?
 

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I did not miss it and still will ask the same question again

What is your point? Design and manufacturing issue? Driver issue ("heavy throttle/engine lugging/infrequent trips etc") or what.

You seem to have a bit of a focus that you understand and maybe we do not understand.
 

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Life is beautiful albeit to short and in this ever changing world we live in if you have the opportunity to enjoy the small pleasures why would one want to become fixated on the oil in and engine to this degree....to many other things in our lives to enjoy
 
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SSBGLA45, I will start by making this statement:

An automobile engine requires lubrication (in the form of engine oil) for purposes of efficiency, reliability and longevity.

Do you agree with this statement?.
 

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Doyall,

First let me say I appreciate your concern and research. I too plan to keep my GLA250 long past the warranty and don't want to see a engine failure at 60K miles. On the other hand, I'm an engineer and used to analyzing data. When I see something that doesn't seem logical, I ask questions as to why. What I see in your data is variability that doesn't follow a pattern with time as one would expect. You established a trend of rising fuel dilution coupled with falling viscosity going from 2076 > 2296 > 2703 miles. BUT the pattern falls apart at 2905 miles. If fuel dilution is truly rising, you should have seen a further increase in dilution and a further drop in viscosity. That did not happen. Fuel dilution fell and viscosity rose. To have that happen, you would either have to add oil (don't think you did), or "boil off" the fuel. Since the trend doesn't follow the established pattern, I'm wondering if there is some variability in how you take the sample. Are you consistent in how you pull the sample? Are all variables like time driven before sample is pulled, engine temperature, etc. held constant? If not, that could be the cause.

May I suggest that you take a couple of additional samples at the same mileage, but purposely alter the variables. In other words, take a sample first thing in the AM before driving and again after a short drive just long enough to get the engine to normal operating temperature.
 
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Discussion Starter · #9 · (Edited)
Boxster,

I certainly appreciate the opportunity to have a substantive, constructive and hopefully, for me at least, instructive discussion with an engineer relating to this entire phenomenon. I am not an engineer and can only benefit from any critique of my methods, techniques and procedures. I am eager to hear any suggestions/recommendations that will yield more accurate test results.

I, like you, noticed what would appear to be an inconsistent relationship between dilution and viscosity found test 8. (Your are correct that there was no additional oil added to the sump. ****, it's making its own - I don't need to add any!) Before starting this adventure I believed, and still believe, that ALL THINGS BEING EQUAL there is a linear relationship between dilution and viscosity. That belief is reinforced to a high degree when the dilution-viscosity results of tests 3, 4, 5, 6 and even 7 are graphed. (Tests 1 & 2 were done with a different fill of oil.) However, test 8 does not follow that same relationship. The only reasonable explanation for this is that oxidation to the oil has resulted in some (minor?) thickening. Oxidative thickening will occur over time and use and will be accelerated by the presence of contaminants (fuel, for instance). This brings into play the all-things-being-equal limitation stressed earlier. Time and persistent contamination (the not being equal part of the equation) have perhaps exerted their effects on the viscosity. (I discontinued paying for oxidation and total base number (TBN) testing after having problems with the lab policy regarding base reference testing. If I were going to undertake extended oil change intervals these parameters would be extremely valuable in the decision making process but I am nowhere near that point yet.)

Relating to evaporation of fuel as a result of extended use (boil-off), please see tests 7 and 8. Both of the samples for these tests were pulled after the conclusion of the same 200 mile trip (100 miles each way with the only stop being for apx. one hour in between) on different days. Test 7 suggests that evaporation does occur to some extent. (That being the case I hate to think how much gas was in the oil prior to the Nov. 24 trip.) I will conclude that after massive dilution occurs that evaporation resulting from extended use is not a viable remediation effort. (I am about ready to conclude that there is no viable remediation that can be undertaken and that the only method to prevent dilution in a gasoline direct-injection engine is extended use after every cold start. I think the engineers who design these things know it and the manufacturers deliberately obfuscate it.)

Relating to testing methodology, I am as rigorously consistent in when and how I do the testing as the circumstances allow me to be.

All samples are drawn within minutes of engine shut-down in order to have all the constituents present and mixed. I purposefully do not pull a sample when the oil is cold for fear that whatever contaminants are present and normally held in suspension will have either fallen out or floated to the surface and I will not get a representative sample. Now, since MB doesn't see fit to give us the ability to monitor any data relative to engine oil temperature, pressure and the like I cannot and will likely never be able to say whether the oil temperature is consistent every time a sample is pulled. However, no sample has been pulled in which the engine has not been run for a minimum of 15 minutes before sampling. While the oil may not be at a consistent temperature between samples or at optimal operating temperature at every sample, the engine has certainly been run long enough to thoroughly mix all the oil and contaminants. I do not see this as a problem but a strict scientific review may suggest otherwise.

As for pulling a sample, after lubricating the barrel of the syringe (see attached picture) with oil from the tip of the dipstick, I insert the probe of the tester into the dipstick tube until it will not go any further. (I hope this is the bottom of the oil pan as I have been using the extraction-through-the-dipstick method of draining the oil for a change.) I back the probe out somewhere between 1 and 1-1/2 inches. I then draw a syringe full of oil and return it to the pan. I draw another syringe full of oil and return it to the pan. I then draw enough oil into the syringe to fill the sample container. The container is then sealed and prepared for mailing. After sampling I will wash the syringe, plunger and tube in hot, soapy (Dawn dishwashing liquid) water, forcing the mixture out through the tube until there is no visible oil remaining. This is followed by a good rinsing with water and air drying. (I draw and return oil before drawing a sample to hopefully mitigate the effects of any possible contaminant left in the equipment from cleaning.) I do not use this syringe, plunger or tube for any purpose other than drawing oil samples.

I am wide open for an examination of my practices and conclusions. I can provide links to resources that will substantiate statements that are made as fact. I need to get my i's dotted and t's crossed before any next phase of this endeavor.
 

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Doyall,

Thanks for the complete description of your method. I should have expected that you would be meticulous on your procedure, but had to ask the question.

It still bothers me about the increase in viscosity, mainly because I have never seen that happen over time. But then again, I work with hydraulic fluids in power steering system, not engine oils that see fuel or combustion by-products.

Good luck with your endeavors to get to the bottom of this. Please keep us informed on your progress.
 

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... It still bothers me about the increase in viscosity, mainly because I have never seen that happen over time. ...
Think engine oil turning to sludge.

This is probably an example of the very, very early beginnings of it. Don't misunderstand me, I am not saying this oil has turned to sludge or even that it will do so under normal conditions. I am simply saying that oxidative thickening is a known and predictable occurrence. MB even has an oxidation specification limit for their 229.5 approved oils (80 abs/cm at 5% fuel dilution). I would imagine a lot of bad things would need to occur for the number to get that high UNDER NORMAL CONDITIONS. (That is the reason an oxidation test is extremely beneficial for extended drains - say 10,000 or so miles.)

Polaris (and virtually every other lab) along with MB obviously thinks 5% dilution is the maximum level considered acceptable. There are plenty of resources out there on the topic to inform yourself with.
 

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SSBGLA45, I will start by making this statement:

An automobile engine requires lubrication (in the form of engine oil) for purposes of efficiency, reliability and longevity.

Do you agree with this statement?.

(bellermb, I want to enjoy the GLA for a long time to come. That is what this is all about for me. Maybe you do not want to enjoy yours as long as I want to enjoy mine and therefore do not care about things such as this.

I to am an engineer who works with speed reducers and during critical failures also analyzes all possible modes of said failure including oil analysis...I am glad you want to enjoy your vehicle as I do as well and thats what I am going to do. Maybe you could explain your end game
 

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Discussion Starter · #13 ·
I to am an engineer who works with speed reducers and during critical failures also analyzes all possible modes of said failure including oil analysis.
Then seriously, post something not only on topic but constructive and please explain to me how such a rapid and massive fuel dilution to an engine's oil is not a detrimental condition.

Maybe you could explain your end game
First, let me say that I continue to hold out hope, however slim it may be, that there is some isolated condition with my particular unit that can be diagnosed and corrected by MB and/or the service department of my dealership. The service manager says she is clueless so it is up to MB to provide guidance. The issue is before them and I anxiously await a response.

That said, one of my goals here is to try to help the community understand that a problem - whether relatively isolated or systemic - MAY exist with their unit that does not present itself in any fashion discernible without more than a superficial computer diagnostic run or by asking if there is any outward manifestation of a problem (i.e. smoke billowing from the tailpipe, massive oil consumption, persistent and unusual noises from the engine compartment, such poor engine performance as to make the car undriveable, etc.. Make no mistake about it, IF fuel dilution is a systemic problem or IF any individual unit suffers from a similar, isolated incidence of fuel dilution, under the right set of circumstances these issues will occur, maybe later rather than sooner, but certainly soon enough to prematurely and unexpectedly cost you a bundle to correct if you do not dispose of your car early enough.) Is helping the community of GLA owners not why this forum exists?

The ONLY way for someone to know if this condition affects their unit is to have testing done. (FWIW, I have absolutely no vested interest in any oil testing laboratory or related industry. Do you have some vested interest in MB or a related industry?) If anyone does decide to do testing for fuel dilution, allow me to recommend using a lab that does gas chromatography (GC) testing as opposed to flash point testing. If people do test and it can be concluded that this is a systemic problem, perhaps a collective voice will be heard at MB that it is unacceptable for a manufacturer of a supposedly premium automobile to put a product in the stream of commerce that is unsuitable for it's intended use without fair notice of the unsuitability. I am not so naive to believe that I alone can get anywhere. But hey, a movement has to start somewhere. Do I think it will start here? Certainly not any more.

So that leaves me with my personal objectives - to determine when I will dispose of this car, to determine if I will ever buy another MB and to determine whether I will ever buy another automobile from the owner(s) of the dealership were I bought the GLA. The answer to all that depends on how each organization handles this. And if the general discussion will help even one person on this forum to make decisions that will prove beneficial to them, it has been worth it.
 

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Can you provide some information on the fuel used....manufacturer? ethanol blend? do you use the same fuel all the time? I will pull a sample from my crankcase and have it analyzed with a lab we use and trust so I can make a independent comparison to the results you have posted in the past......probably won't happen till the new year though....
 

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Discussion Starter · #15 ·
Can you provide some information on the fuel used....manufacturer? ethanol blend? do you use the same fuel all the time? I will pull a sample from my crankcase and have it analyzed with a lab we use and trust so I can make a independent comparison to the results you have posted in the past......probably won't happen till the new year though....
The overwhelming majority of gasoline used is from Costco (my best guess is that it is refined/blended by either Valero or Motiva with Costco adding their own additive package on-site), 93 octane, 10% maximum ethanol per labels the pump. The only time non-Costco gas is used is during an out-of-town trip.

For the benefit of non-gear heads - obviously not you bellermb - who may have been reading this thread only for the barbs that have been flying and may not understand how this fuel dilution phenomenon comes about short of the operational parameters that have been discussed, I am going to work on another post and attempt to explain it the best I can. (I will also expound on my perceived problem with MB.) Hopefully it will benefit at least one person. But I do invite you, no beg you, to review and critique, correct or qualify any of my statements of fact that need it and challenge any of my assumptions, suppositions, conclusions and the like. I want to be as educated as I can be and have no problem taking constructive criticism. But if you do provide some feedback, please do not merely say "that is wrong," explain why it is wrong.
 

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Discussion Starter · #17 ·
Have you purchased and read this paper on the subject......
To be honest with you, after reading the intro I am kind of afraid to.

But I think I will wait until after I post my diatribe and see if I can get shot down in any of my postulates.
 

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Discussion Starter · #18 ·
...But I think I will wait until after I post my diatribe ....
As it is turning into a bit of a long rant that veers off from the original post, I am going to start a new post altogether. Be on the lookout. Don't say you were not warned.
 
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