Also glad to know that I am not the only one. I just changed my oil the other day and the motor gets drastically quieter. It makes me cringe to think about the amount of wear that must be happening when I can actually hear changes in the engine noise from rotation when the oil is getting worn.


I have posted about this before and this is the second time someone told me that the sound is just the timing chain.

 

I've also noticed what sounds like increased valve chatter as the oil ages. The thing sounds like a diesel chugging away. I suppose it may be the timing chain, but if it is it is another thing Mitsubishi designed poorly. The timing chain on my Si is completely silent.

 

Hey Giz, Thanks for posting results. First, the silicon levels being significantly down is definitely goodnews; the 5% fuel dilution is not. Can you recall the relative weather conditions between these two oil changes/ Specifically, was this when the weather was the coldest? I know you are in Portland so your winters are mostly rain but I am guessing here. What I am asking is, could the weather during the first change, which had 2% fuel dilution been warmer than the last where you had 5% fuel dilution?
Regardless, keep looking for I am hopeing that after ~10-15K mi this problem will be significantly reduced. I have 12K mi on my car and switched to AMSOIL Signature last change; got my oil kit recently and next change will test for dilution and wear parameters; hopefully they will all be "low".

Later, Ken

 

NMW Tech, thanks for the info. Thankfully for most people, there will not be any chain stretch. It's only when poor maintenance has been taken on the car, like the car in your example, or the car has been driven crazy hard and even then it is unlikely that the chain will have stretched. It is always a "check and leave it alone if nothing's wrong" deal. Thankfully, it doesn't look too terribly hard if it does need to be done, but that valve lash adjustment procedure that also happens to come up around 60k looks like no fun. In any case, here's the training video on how the timing chain procedure is done, if anyone is interested: http://www.youtube.com/watch?v=JX6Z3...eature=related. Anyone got any videos on the valve adjustment procedure?

 

Actually, I'm in Ohio. The break-in oil was in the car from April through August. The second sample was from August to the end of January. The oil that suffered the 5% fuel dilution saw significantly colder temperatures. The first change saw a low temp. of maybe 50-60 *F, while the second got down to maybe 0 *F on a few occasions.

Ohio winters aren't particularly cold, and the summers are not so hot, but those two samples were changed basically along season lines. To answer your question, the first change saw significantly warmer weather.

 

Ooooppps, must have eaten the wrong thing for I somehow got your geographic location a bit messed up, LOL!
That said, your results seems to show, perhaps the obvious, that, when cold, the fuel is definitely pouring in there more than when warm in proportion to the length of time the engine is in cold start portion of the fuel maps where the A/F are low. So our northern brothers in Canada should be getting the maximum fuel dilution during the winter, Miami the least.
In short, we cannot control the weather but we can adjust to it by changing the oil more frequently in the winter than the summer. How much more frequently, you ask? Lower the miles between changes such that you get at most 2% fuel dilution, assuming we have settled on this figure as the max allowable level of dilution.

Later, Ken
Edit: The question is, does excess fuel enter the engine when warm and there exists low A/F conditions? Tuned vs untuned, to date, says no but more results/cars are needed to confirm this.

 

If we believe the discussion and results from earlier in the thread, the percentage of fuel dilution has little to do with total miles driven. It can fluctuate up and down depending on how the car was driven before the sample was taken. While the high numbers we're seeing seem to be indicative of a larger problem, the major item you want to watch is the viscosity change.

For example, you may have an instantaneous measurement of 1% fuel dilution, but over the life of the oil it has hovered around 3-4% on average. This may have caused a change in viscosity that is more serious than the current 1% fuel dilution would seem to indicate.

This is why I have updated the spreadsheet to remove any mention of a correlation between fuel dilution and miles driven.

 

Yes, I am with you on this but I still think the cause for the differences in fuel dilution between your oil changes is related to seasonal/ temperature differences despite the fact %fuel dilution is dynamic. I tried earlier to dismiss fuel dilution for this reason and suggested we should focus on the concentration of wear metals, like Al which accumulate over time, but I believe it was Sublgt that supported % fuel dilution as a good measure of the problem. If this suggestion is true, then you/all of us should see less fuel dilution this summer i.e., you should see 2% or less this summer.

Later, Ken
Edit: The miles between oil changes where ~ the same (yes?) and 5% had greater viscosity loss than the oil with 2% (?yes).

 

My first oil change oil was darker than a car full of assh0les... but its been getting better... now @ 2200 miles and about to do oil change number 2... still dark when i check it .. but not as bad... welcome to an evo haha

 

My change intervals were within 400 miles of each other (4600 vs. 5000), and the 5% change had a greater viscosity loss. However, I also know that I made 6-10 short trips just prior to to the change as I drove around trying to find someone (anyone!) that had Mobil 1 in the correct weight. Earlier discussions showed that this would have increased my fuel dilution. While the fuel dilution level is important, the viscosity change is what is ultimately going to cause problems and you can have reduced viscosity from high fuel dilution levels even if your fuel dilution at the time of sampling was low.

We, as well as Mitsubishi, seem to think this has something to do with the cold. I would also expect to find reduced levels this summer.

I'm having trouble deciding if I should take it back to Mitsubishi and complain or not. If they do their own tests now, it's unlikely to be as bad since it's been warm. Plus, I've got some parts and a custom tune waiting to be performed. I'm inclined to plug my ears, go "LaLaLaLa," and hope it goes away with a proper tune (despite the findings of our one data point to the contrary). Of course, I would keep an eye on it and change more frequently.

On the other hand, maybe I should get it documented prior to making any mods even though it's a PITA.

 

I just performed my first oil chane at 1050 miles oil was black and did smell of gasoline. I changed with redline oil cuz i got a great deal on it. Car does feel a bit smoother but not considerably.

 

Results from my second oil change and sample. Numbers look almost identical to the first test, near same mileage on both samples. First test was at 2440 miles total sampling the outgoing factory fill. Second test is with 2345 miles on Mobil 1 5/30 (4785 miles total).

Most of the last sample period (>90%) was with a AP Stage 1 map installed.

From the first sample: wear metals dropped, silicon dropped, viscosity is slightly lower, the fuel dilution is identical and the additive packages are lower in the current sample.

 

Gizmotov, viscocity drop really isn't much of a concern unless it is causing increased wear metals. I have talked in great detail with Polaris Labs, which is who Oil Analyzers uses, and their comments were that 4% and less isn't really that much of a concern as long as wear metals are low. It's when fuel dilution is higher than that that viscocity tends to drop to more critical levels, but even then, viscocity isn't really the issue. Again, it's wear metals that are the concern. If viscocity is low, but wear metals are fine, you have nothing to worry about.

What's most important at the end of the day is the quality of the oil that you are running, because what really matters more than anything else is film strength. Now, I am not saying that the fuel dilution isn't a concern, it is; hell, I'm the one who started this thread. I change my oil every 2k miles because of this very issue, and I will continue to do oil analysis to see if the condition improves, especially since I'm tuned now. Other than that, I'm not really worried about it. Just run a good quality oil, 20 or 30 weight, and keep an eye on it with oil analysis.

 

So Dave is the level of concern now been changed from 2% to >4%? Recall Oil Doc was saying anything above 2% was of concern.
This may be an issue of semantics but I think viscocity loss is the problem with fuel dilution, the consequences of which are reduced lubrication which results in excessive wear as evidenced by higher concentrations of selected metals in the engine's oil. So I would say the process of viscocity loss is the issue with concern being reached when metals indicative of associated wear begin to rise over background levels. What I think you are saying is fuel dilution and assoicated reduction in viscocity is not of concern IFF the concentration of specific metals do not significantly increase.
Yes, you are correct, I am a bit **** when it comes to interpretation! Just can't control myself LOL.

Later, Ken

 

Yes, that is what I am saying. From talking with the experts at various labs, there comments are along the lines of this: Viscocity will drop with fuel dilution. No doubt about it. However, that really isn't the concern unless it has dropped substantially and no, dropping one grade is NOT substantial. What you need to be worried about is wear metals, and these result not so much from viscocity drop, but from the oil itself breaking down and then not providing proper lubrication. If the oil breaks down, it loses film strength. When film strength is compromised, the oil will have a tendency to wash off the metal surfaces too easily and metal to metal contact will occur.

This is what causes increased wear metals, so if wear metals are low despite viscocity dropping then you know that the oil is still holding up fine. If anyone is interested, here is a chart that shows how oil weights are determined. It's called a centistoke scale, and it shows how there is a wide range of actual weight that will fall into each classification. http://www.bobistheoilguy.com/visc.html As you can see, a 30 weight oil can range anywhere from 9.3 - 12.49, while a 20 weight can range from 5.60 - 9.29. So, as you can see, there are some 20 weight oils that are about the same weight as some 30 weight oils.

A perfect example is the AMSOIL SSO 0W30, which is about 10.2, while the Racing Dominator RD 5W20 is about 9.1, so they are only off by about a point and are almost the same weight oil. I am actually switching over to this in a few days, because after talking with Oil Doc and his contacts at the tech department at AMSOIL, the comments are that the RD 5W20 is the hot ticket for a car like the EVO. Even though it's a 20 weight, again, it's on the high side for a 20 weight and close to a 30 weight.

More importantly, the additive packs and film strength are outstanding, and even with it's lighter weight (which again is marginal), it's meant to handle levels of heat, abuse, and fuel dilution that the SSO can't (which is impressive, because the SSO is an incredible oil and will hold up under horrendous conditions). Now, this comes with a caveat, but one that really doesn't affect us EVO guys anyway; unlike the SSO, it is not suitable for extended drain intervals but that's not an option for us anyway because of the fuel dilution issue and because of the fact that it's a performance car and extended drain intervals aren't meant for cars like this anyway.

I will report back on my next oil analysis to see how this oil holds up, but my guess is the results will be slightly improved upon the already great results that I got from the SSO. Will keep all posted... AMSOIL FTW!