Fuel Dilution Everywhere

[irollturbo]

I have been getting flagged with excessive fuel dilution in every sample I send to Oil Analyzers. This is happening on 3 different vehicles with no changes to driving environment.

Car #1 is a 2000 Volvo S70 GLT, 67K miles on car
4/2011 Analysis with 3400 miles on oil showed 4.7% dilution and 61 on oxidation. TBN 3.59
9/2010 Analysis with 5400 miles on oil showed 4.5% dilution and 51 on oxidation. TBN 2.05
2009 analysis showed 1.8% and 2.9% dilution. Before that no dilution to speak of.

Car #2 is a 2004 Volvo V70R, 124K miles on car
4/2011 Analysis with 4991 miles on oil showed 3.2% dilution and 63 on oxidation. TBN 2.90
9/2010 Analysis with 8036 miles on oil showed 3.8% dilution with 50 on oxidation. TBN 4.39
2009 analysis showed 1.8% dilution. Before that no dilution to speak of.

Car #3 is a 1993 Volvo 240 (non-turbo), 148K on car
4/2011 Analysis with 3222 miles on oil showed 4.3% dilution and 44 oxidation. TBN is 5.05
All previous reports had no fuel dilution to speak of.

Oil is Amsoil S2000 OW30

All cars are running well. No starting problems. No idle problems. No smoke.
A 20 minute long OBDII data log analysis of the S70 showed the car to be running exceptional well with all fuel ratios where they should be.

Given that I am see similar reports across three different cars my first reaction is to call [censored] on these lab results. The lab re-ran the test on at least the Volvo 240 and came up with the same result. I probably just dumped this oil after 7 months needlessly.

Before I run off and start chasing mechanical ghosts can anyone make any sense of this? Any other experiences like this out there. Is there anything that can lead to a false result?

It was suggested that I look for fuel injector leaks or crankcase ventilation problems. To see this on three different cars really makes me question that, especially since the cars are all running well.

 

[Y_K]

Any change in fuel composition?

 

[JimPghPA]

1) What lab did you use?
2) Did you let those vehicles idle to get the interior warm before using them?

 

[Y_K]

1) Oil Analisers

 

[irollturbo]

1) Oil Analyzers (who answers the phone as Polaris)

2) It was 80-90 degrees the day I took the samples. Two of the cars were driven 30 miles in the morning and the oil was still quite warm when I changed it. The Volvo 240 had been sitting for a couple weeks, but was driven 7 miles before taking the sample.

As far as the fuel goes I have been using Shell more than I have in the past. I had usually used Mobil or Chevron. And then there is the switch to the E10 stuff over the past several years as MTBE is a thing of the past.

 

[SubLGT]

Take another sample from one vehicle, send half to Blackstone, other half to OAI, and compare the results.

Are you using any fuel or oil additives?

 

[irollturbo]

All of the oil is drained and sitting in containers now. So I'll have to wait until next time if I want to do a lab compare.

I use Amsoil PI periodically, but this is nothing new.

I am using the Autorx Maintenance dose in the oil.

Originally Posted By: SubLGT
Take another sample from one vehicle, send half to Blackstone, other half to OAI, and compare the results.

Are you using any fuel or oil additives?

 

[Pablo]

All three (especially the two white blocks) are known to throw fuel.

Did I miss your sampling technique? These cars need to be run hot and HARD before sampling. 7 miles may not be enough. I'm not kidding. The oil has to be HOT for a good while.

 

[Eddie]

I don't believe in doing a "special" hot run before taking a sample. I want a representative sample for the way the vehicle is used-JMO. The data shown is suspect as all the vehicles show high and approximately the same level of fuel. Ed

 

[ltslimjim]

^I believe Pablo's point is that if you sample after a good long 30-40 mile round trip from/back home and sample, still have fuel show up in a UOA like you did...THEN it finally tells you something. Most cars, AFAIK, will show fuel in the sample if draw cold or even more so perhaps if driven very little(the epitome of short tripping/severe service).

Another ironic relation to the 'most wear occurs on startup' bit. Perhaps even warm up time included, because the vehicle is using more fuel because it's in open loop in relation to your a/f ratios/emissions system components etc. So of course you are going to get high fuel readings starting the car and idling it or just driving it a 'few' miles. The temp gauge moving doesn't tell the entire story.

 

[Eddie]

My point is that I want to sample engine wear as the top priority. If engine wear is abnormal then I want to know why. If I skew the sample by doing a special hot run then, I don't really know why the wear is high. JMW. Ed

 

[irollturbo]

The samples were taken through the oil dip stick. Last year they were taken while the oil drained.

Prior to last year it never matter how I sampled or how much I drove before taking the sample. Even a quick trip around the block was fine and no significant fuel content was noted in the oil...

Originally Posted By: Pablo
All three (especially the two white blocks) are known to throw fuel.

Did I miss your sampling technique? These cars need to be run hot and HARD before sampling. 7 miles may not be enough. I'm not kidding. The oil has to be HOT for a good while.

 

[Pablo]

Let's take one car for example:

2009 1.8% then 2.9%

This a significant amount of fuel. What was the viscosity (fresh and used)

2010 4.5% fuel

Again huge, oil viscosity?

2011 4.7% dilution

Oil viscosity?

I doubt an accredited lab over 2-3 years had repeated errors and they only were on your cars. I think we need to discuss the causes of your fuel dilution. Do you do a lot of short trips? How fast does your thermostat get to hot?

 

[irollturbo]

2009 viscosity was 9.4 then 9.6
2010 viscosity was 9.7
2011 viscosity was 8.9

Oil is Amsoil S2000 0W30 (for new oil reference)

Yes, I do a lot of short trips. Again, nothing new. And it is boiling hot here for a good chunk of the year. Even in winter the car is usually warmed up by the time (per thermostat) by the time I get a mile or two down the road.

In the data log I mentioned, the cold start was 85 degrees - that's April.

The turbo cars are also Stage II IPD modified, but that is not a new thing either.

It was suggested to me to leave a fuel pressure gauge in place over night and look for pressure loss in the fuel system. But given that the cars practically start on the first crank, I'm not sure whether this would be a useful exercise or not.

It was also suggested that I check the PCV systems. I have suction at the oil caps on all cars. Not sure if that's a fool proof check, but there are at least no really bad clogged PCV symptoms.

Not to knock the oil analysis, but in the past I have noticed other inexplicable multi-car themes. One time it was oil thickening. Another time it was Nitration. And then the theme would vanish as fast as it started. Makes me wonder about how accurate this analysis stuff is....






Originally Posted By: Pablo
Let's take one car for example:

2009 1.8% then 2.9%

This a significant amount of fuel. What was the viscosity (fresh and used)

2010 4.5% fuel

Again huge, oil viscosity?

2011 4.7% dilution

Oil viscosity?

I doubt an accredited lab over 2-3 years had repeated errors and they only were on your cars. I think we need to discuss the causes of your fuel dilution. Do you do a lot of short trips? How fast does your thermostat get to hot?

 

[Pablo]

Originally Posted By: irollturbo
2009 viscosity was 9.4 then 9.6
2010 viscosity was 9.7
2011 viscosity was 8.9

Oil is Amsoil S2000 0W30 (for new oil reference)


I would say with those lower viscosities the fuel dilution is real. Especially with S2K and it's previous propensity to increase viscosity one grade with use.

 

[irollturbo]

OK. Thanks. Will let you know what I find out.



Originally Posted By: Pablo
Originally Posted By: irollturbo
2009 viscosity was 9.4 then 9.6
2010 viscosity was 9.7
2011 viscosity was 8.9

Oil is Amsoil S2000 0W30 (for new oil reference)


I would say with those lower viscosities the fuel dilution is real. Especially with S2K and it's previous propensity to increase viscosity one grade with use.

 

[irollturbo]

Quick update. On the V70R the PCV system seems to be working ok - there is suction at the oil cap.

I tested the fuel pressure. 47psi at idle. After about 3.5 hours sitting, the pressure dropped to 23psi. I have no idea if that level of leak down is normal.

-Ted

 

[irollturbo]

Quick update. My Dad has a 2005 Volvo S60R with 65K and submitted his oil to Oil Analyzers for analysis. This sample went to a different location as he is in a different part of the country. His results were almost identical after 4000 miles to what I have posted previously for the 2004 V70R. Rather than believe that these four cars which run otherwise perfectly have become afflicted with the same mechanical problem, I am more apt to believe that there has been some change to testing methodology somewhere along the line. It may be that these cars are prone to this behavior and the dilution was there all along, and the testing methodology just became more sensitive. I don't know. Given that the wear numbers are good I am done worrying about this and do not plan to pursue any mechanical investigations further.

 

[demarpaint]

I often wondered why a UOA sample isn't taken exactly as the the car is used. In other words, if a car is used for 10 minute drives all the time, why drive an hour to get the oil good and hot before sampling? Log 3000 miles, take a 10 minute drive and sample the oil, send it off for testing. Isn't knowing the condition of the oil, based on driving conditions the best? A one hour drive will skew results.

 

[INDYMAC]

Originally Posted By: demarpaint
I often wondered why a UOA sample isn't taken exactly as the the car is used. In other words, if a car is used for 10 minute drives all the time, why drive an hour to get the oil good and hot before sampling? Log 3000 miles, take a 10 minute drive and sample the oil, send it off for testing. Isn't knowing the condition of the oil, based on driving conditions the best? A one hour drive will skew results.


I agree. Doing anything out of the ordinary offers little in the way of corrective measures and re-evaluation on subsequent UOA's.