View Poll Results: Which best describes your oil when you wipe the dipstick on a napkin?
It's dark after less than 1000 miles and it smells like fuel.
119
56.13%
It's maybe a little dark, but I don't really smell fuel.
65
30.66%
Clean as a whistle
28
13.21%
Voters: 212. You may not vote on this poll
Fuel dilution in oil problem
Dec 5, 2008, 01:32 PM
#1
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Fuel dilution in oil problem
I was wondering if anyone else is having issues with this. Tell tale signs are oil turning dark very quickly after an oil change, accompanied by a gasoline smell in the oil. Now, mitsu released a TSB a while back about fuel dilution issues saying that if the engine is run hard while still cold that excess fuel can get into the oil. Here is the problem, it appears that it's not just when the engine is cold. I NEVER dog my car while it's cold, yet my oil still smells like it has fuel in it and turns very dark very quickly after a fresh oil change; far sooner than it should.
I spoke with the Oil Doc, and he is sending me an oil analysis kit to check to see if this is what's causing my issue, but I feel pretty certain it is based on 3 important details: First, when I wipe my dipstick on the paper towel to check the level, it smells like fuel and is dark after less than 1000 miles. 2, mitsu released a TSB about this but seems to be offbase about it only happening when the engine is cold, and arguably the most convincing is 3, fuel dilution is usually caused by OVERLY RICH A/F CONDITIONS! We all know that the X has major problems with this, and although the latest factory reflash helped a tiny bit, it's still WAY TOO RICH; dipping down into the 9:1 territory under full load at mid to high rpms.
What happens is that under compression, if there is too much fuel in the combustion chamber, some of it slips past the rings and gets mixed into the oil around the pistons. As the pistons go up and down, the rings "squeegee" the old oil back into the oil supply, thus mixing the now fuel diluted mixture back into the oil supply. It would seem that now there is yet another benefit to getting a tune; not only will the car run better without the stupid hesitation issues, it will make more power AND prevent excess fuel from getting into the oil. Now I need to wait until I am at my 3000 mile mark on this current oil change and I've got 2k to go, so I wont be able to post the results of the oil analysis for a while but I am pretty sure my suspicions are right.
I can't be the only one that this is happening to. Does anyone else's oil turn dark very quickly even after a fresh oil change and smell like fuel? I'd like to see how many people this is affecting, because I am guessing it's most of us and this is a major problem. Fuel will break down oil and cause it to not provide protection to major components, which for obvious reasons is not good. BTW, I am using AMSOIL SSO 0W30, one of the finest oils on the market so I know it's not that. The same thing happened on my mobile 1 factory fill, so there's the "control" in this test. Ok, chime in people.
I spoke with the Oil Doc, and he is sending me an oil analysis kit to check to see if this is what's causing my issue, but I feel pretty certain it is based on 3 important details: First, when I wipe my dipstick on the paper towel to check the level, it smells like fuel and is dark after less than 1000 miles. 2, mitsu released a TSB about this but seems to be offbase about it only happening when the engine is cold, and arguably the most convincing is 3, fuel dilution is usually caused by OVERLY RICH A/F CONDITIONS! We all know that the X has major problems with this, and although the latest factory reflash helped a tiny bit, it's still WAY TOO RICH; dipping down into the 9:1 territory under full load at mid to high rpms.
What happens is that under compression, if there is too much fuel in the combustion chamber, some of it slips past the rings and gets mixed into the oil around the pistons. As the pistons go up and down, the rings "squeegee" the old oil back into the oil supply, thus mixing the now fuel diluted mixture back into the oil supply. It would seem that now there is yet another benefit to getting a tune; not only will the car run better without the stupid hesitation issues, it will make more power AND prevent excess fuel from getting into the oil. Now I need to wait until I am at my 3000 mile mark on this current oil change and I've got 2k to go, so I wont be able to post the results of the oil analysis for a while but I am pretty sure my suspicions are right.
I can't be the only one that this is happening to. Does anyone else's oil turn dark very quickly even after a fresh oil change and smell like fuel? I'd like to see how many people this is affecting, because I am guessing it's most of us and this is a major problem. Fuel will break down oil and cause it to not provide protection to major components, which for obvious reasons is not good. BTW, I am using AMSOIL SSO 0W30, one of the finest oils on the market so I know it's not that. The same thing happened on my mobile 1 factory fill, so there's the "control" in this test. Ok, chime in people.
Last edited by STi2EvoX; Dec 5, 2008 at 01:43 PM.
Dec 5, 2008, 01:52 PM
#2
My oil was changed about 1k miles ago. I checked it at the last fillup (tuesday?) and it was already dark. I never really notice the fuel smell, but my car runs SUPER rich.
I change my oil every 3-3.5k miles because of how rich it is. There is likely a ton of fuel left unburned in the cylinder when the piston moves up...
I wonder how long until engines start going boom from the issue.
On the more boutique oils like Amsoil, which are more "slick" and a bit "thinner" for a given rating, is the issue potentially worse? I know that on high mileage NA motors, moving to a thinner oil can cause more blow by and quicker wear.
ETA: I need to check my spark plugs too. I can't imagine that this much unburned fuel is doing them any favors.
I change my oil every 3-3.5k miles because of how rich it is. There is likely a ton of fuel left unburned in the cylinder when the piston moves up...
I wonder how long until engines start going boom from the issue.
On the more boutique oils like Amsoil, which are more "slick" and a bit "thinner" for a given rating, is the issue potentially worse? I know that on high mileage NA motors, moving to a thinner oil can cause more blow by and quicker wear.
ETA: I need to check my spark plugs too. I can't imagine that this much unburned fuel is doing them any favors.
Dec 5, 2008, 01:58 PM
#3
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Thread Starter
The amsoil SSO 0W30 is actually not a thinner oil. It's still a 30 wgt, the only difference is that a 0w30 will flow quicker on cold starts than 5w30. Remember, when reading oil ratings, the first number is wgt when cold, the second is at operating temps. While you may be right that the higher quality "boutique" oils are a bit slicker for a given rating, I don't think that's the issue because the same thing happened to my mobile 1 factory fill.
Dec 5, 2008, 02:08 PM
#4
The amsoil SSO 0W30 is actually not a thinner oil. It's still a 30 wgt, the only difference is that a 0w30 will flow quicker on cold starts than 5w30. Remember, when reading oil ratings, the first number is wgt when cold, the second is at operating temps. While you may be right that the higher quality "boutique" oils are a bit slicker for a given rating, I don't think that's the issue because the same thing happened to my mobile 1 factory fill.
My impression with the amsoil/royal purples/etc. is that they are nominally the same weight as "conventional" oils, but due to their formulation, they "feel" thinner (and between that and the "slicker" they lubricate differently). I'm wondering if the smaller molecules can potential exacerbate any issues re: fuel in the oil.
Dec 5, 2008, 02:19 PM
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Here is what I have come up with....
I will post more later.... You need to get a copy of the TSB 08-13-011 and take it to the dealer with you...
They should change your oil at no charge as the oil needs to be replaced before they reflash your ECM... let them put the Mobil 1 in it to make sure they have the problem fixed before switching back to my SSO
My Tech Dept wants you to get this done ASAP as you can smell the fuel..
We also checked out some other forums while we were on the phone and found similar complaints... Also one where they just flashed the ECM without oil change and had dismall results..
Do not put this off....
Doc
I will post more later.... You need to get a copy of the TSB 08-13-011 and take it to the dealer with you...
They should change your oil at no charge as the oil needs to be replaced before they reflash your ECM... let them put the Mobil 1 in it to make sure they have the problem fixed before switching back to my SSO
My Tech Dept wants you to get this done ASAP as you can smell the fuel..
We also checked out some other forums while we were on the phone and found similar complaints... Also one where they just flashed the ECM without oil change and had dismall results..
Do not put this off....
Doc
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Dec 5, 2008, 03:12 PM
#9
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Thread Starter
Here is what I have come up with....
I will post more later.... You need to get a copy of the TSB 08-13-011 and take it to the dealer with you...
They should change your oil at no charge as the oil needs to be replaced before they reflash your ECM... let them put the Mobil 1 in it to make sure they have the problem fixed before switching back to my SSO
My Tech Dept wants you to get this done ASAP as you can smell the fuel..
We also checked out some other forums while we were on the phone and found similar complaints... Also one where they just flashed the ECM without oil change and had dismall results..
Do not put this off....
Doc
I will post more later.... You need to get a copy of the TSB 08-13-011 and take it to the dealer with you...
They should change your oil at no charge as the oil needs to be replaced before they reflash your ECM... let them put the Mobil 1 in it to make sure they have the problem fixed before switching back to my SSO
My Tech Dept wants you to get this done ASAP as you can smell the fuel..
We also checked out some other forums while we were on the phone and found similar complaints... Also one where they just flashed the ECM without oil change and had dismall results..
Do not put this off....
Doc
). I got it before my last oil change before this one, so... 2 oil changes ago. It doesn't lean out the A/F enough to make any difference. Mitsubishi did put out a different TSB a while back stating that the X has issues with fuel dilution when driving the car hard if the engine isn't fully warmed up, but with how rich the A/F ratios are in general, they are wrong that it only happens when it's cold. Something has to be done about this ASAP.
Dec 5, 2008, 03:31 PM
#10
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many times it can be faulty injectors or dirty ones staying open causing fuel tp pass through and dilute the oil ( this happened to my friends 2jz and spun the bearing because the oil was to thin)
Dec 5, 2008, 04:02 PM
#12
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Right I understand. I wasn't saying that the amsoil was causing it (since I only use Mobil 1 and have the same thing going on).
My impression with the amsoil/royal purples/etc. is that they are nominally the same weight as "conventional" oils, but due to their formulation, they "feel" thinner (and between that and the "slicker" they lubricate differently). I'm wondering if the smaller molecules can potential exacerbate any issues re: fuel in the oil.
My impression with the amsoil/royal purples/etc. is that they are nominally the same weight as "conventional" oils, but due to their formulation, they "feel" thinner (and between that and the "slicker" they lubricate differently). I'm wondering if the smaller molecules can potential exacerbate any issues re: fuel in the oil.
Try to imagine this.... Crushed gravel like 3/4 chip... oval shaped marbles and then finally marbles... Petroleum oil, Hydro-Cracked oil and PAO or Ester oils.
Not so much that the molecules are bigger or smaller, just more precise in shape where they easily move past each other.
Then we have to look at how petroleum oils are full of Paraffin (Wax) natuarally, Hydro-Cracks have to be de-waxed and PAO's and Esters are produced wax free which is why petroleum oils solidify quicly below 32 degrees...
OK.. I got a little off track here... anyhow... there are a lot of misconceptions about the differences in oils...
The fact is, the problem needs to be fixed, the oil needs to be changed BEFORE the ECM is flashed and if you smell fuel, Do Not pass Go or it will cost you a lot more than $200.00
Doc
Dec 5, 2008, 04:06 PM
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So, you know there is a problem that is contaminating the oil, the oil is suppose to be changed at 3K and you are going to wait to 5K...
Does this make sense to anyone here ?
Doc
