< 2% is generally the guideline for fuel dilution (although 0 or < 0.5 would be ideal). Silicone depends more on the specific car, and I'm not sure that enough evo x's have done analysis to say what is normal. From other cars, silicone <= 10-15 appears to be the average. Copper should also be <= 10-15. SUS Viscosity at 210 deg F should be between 56-62. CsT Viscocity at 110 should be 9.1-11.1.

Those posted results don't look good, but may be due to break in. Did they give you a commented analysis of what may be going on? Blackstone Labs usually gives some useful textual feedback.

 

Just an idea but maybe mitsu is doing this on purpose. They know that this car is aimed at a audience who is interested in after market modification and they run it this rich to have less hp so they can avoid being taxed according to hp.some one said 9-1, and why would they do that when best is 12-1(best power ratio) It's a easy fix with a tune and possibly they know that. OR i can be terribly wrong about all this.

 

Stoichometric is 14.7AFR

 

Stoichiometric is 14.7:1. This is the ideal A/F ratio for cruising conditions to get the best fuel economy. Combustion temps/EGTs are low in this condition so it's safe to run that lean. Gasoline makes the best power at about 12:1, and many NA cars will run this this high for WOT use to creat the best HP. Turbo cars generate a lot more heat and have higher combustion temps than an NA car, so it's wise to go a little bit lower to prevent detonation, especially at high rpms.

Many tuners would say that the best A/F ratios to run on an evo are as follows: during spool up, running around 12:1 and tapering it down to about 11- 11.3 at redline. Every single car, imparticular high compression NA engines or high boost turbo engines, are going to suffer from slight oil consumption and fuel dilution issues. Usually, if the rings are in good shape and the A/F ratios are not too rich, it's very mild and unnoticeable. The X suffers from a very bad tune from the factory that runs way too rich of an A/F ratio and it's inexcusable for mitsu to have released the car in this shape.

A tune fixes this, but it's a shame that mitsu makes us go that route. Mitsu needs to wise up, because I forsee that on the stock tune, people will be fouling spark plugs long before the manual implies, and rod bearings and things of that nature could fail from improper lubrication due to fuel dilution if the oil isn't changed early. This is probably part of the reason that mitsu changed the oil change intervals from 5k to 3k regardless of whether the driving conditions are severe. Anyone wanting to change their oil at 5k after knowing this is stupid and just asking for trouble.

Mitsu will most likely not do anything about this until it comes time for a model update in 09 or 2010. The rest of us will just have to deal with it, or get a tune for better peace of mind (and the huge boost in power is a nice added bonus!).

 

Fuel Dilution should be given in % on Analysis Reports

Royal Purple shears on it's own too quick, much less with the help of fuel dilution. I would suggest an immediate change most likely with Mobil 1 EP for now and keep your records. I would also highly recommend Oil Analysis, $22.55 from me for a postage paid kit from Oil Analyzers Inc. You should be able to file those costs under a warranty when they figure out a cure. They have already shown fault with a TSB on it, just make sure you take it in and GET paperwork... No Matter What They Say... GET Paperwork...

Didn't look at your report but, It should be Silicon (Dirt) on your report, not silicone, and 90 is well within limits... MAX Fuel Dilution is 2% . Although, Silicone is used as an Anti-Foaming agent in oils.

See above

 

My previous car was a mazdaspeed 6, and it was tuned like poo from the factory. I fouled my first plug at 5k miles. I foresee this happening with evos, as well. At least we have some decent, easy aftermarket solutions.

 

looks like alot of people are having this issue...

any word on mitsubishi fixing this??

 

It sounds like a tune is the best bet. From what I understand, at WOT, the X runs something like a 9.5:1 AFR.

I'm saving my pennies for an AccessPort now, partially for this reason (at least that's what I'm telling my wife). The extra power sure doesn't hurt, either

 

9-5-1 !!! wow

thats just not right...

what is the sti ? or the srt-4?

 

i just picked up that mobile 1 extended service 5-30

good for 15,000 miles

that should add some extended protection..

 

i thought my smell was the clutch burning smell... maybe I should double check

 

so what am i supposed to do...??

what did you guys do, that are experiencing the same issue??

 

I would do what scottatayamaha said above. Oil changes every 3k, and also I would send your oil off to get analyzed the next time you change it. I like www.blackstone-labs.com for oil analysis. You can request a free kit for sending in your sample from their site.

 

i had the same problem on my X. I just sent my analysis in and waiting on my results. i'll post up if you guys are curious.

 

Ok, We still do not have STI2EVO's results which would be a good comparison to Q15H results since NMX suggests an engine with low miles may have a higher % of fuel in the oil; in short, is this 2.4% dilution just transitory? What we also need, other than more results (more replicates), is the same analysis for a well broken in engine with a tune to see if an expected reduction in % fuel dilution actually occurs. For my next oil change, I'll collect an oil sample to test for this condition for I have >10Kmi and a tune. As a minimum, we should compile a significant amount of replicates (five vehicles) for these four treatment conditions: low miles, w/o tune; low miles w tune; high miles w/o tune; high miles w tune and associated % fuel dilution (and other relevent data from the analysis; Doc, what should those other vaariables be?) and then send same to Mitsu for purposes of documenting the (1) fuel dilution problem, (2) possible source/cause of this problem (i.e., A/F with accompanying examples which have been presented on EVOM) and (3) effects of an aftermarket tune on reducing (assuming it occurs) the amount of fuel in the engine oil. By so doing this will provide the data base against which claims can be made in the event the observed oil dilution results in longevity issues with the 4B11T engine. In addition, such information should provide sufficient cause for Mitsu to reevaluate their factory tunes for the next generation of EVO X as well as some additional TSB's for a less rich tune, something similar to our aftermarket tunes.

What is interesting is I got "flamed" like no tomorrow when I questioned, some time ago, why the factory tune was so rich. All I got was, "Mitsu did this to protect the engine from detonation in the extremes of environmental conditions (altitude, temperature, etc.)". Well it now appears that this "tuning strategy" may, in fact, jeporadize the engine from a completely different cause, namely fuel dilution.

Later, Ken
Edit: In short, it appears Mitsu when riding the line between detonation and fuel dilution has opted towards the latter perhaps too far.