Used Oil Analysis (UOA) or Analyses and Extended Oil Change Interval

A library of VOA at BITOG:

http://theoildrop.server101.com/forums/pos...amp;Board=UBB11

 

There are quite a few analysis with fuel dilution problems. Yet, Jayman never has any. I am sure he is using good sampling technique. Does anyone else know the circumstances of the sampling that resulted in the fuel dilution?

BTW, thanks for the oil info.

I only have a few hundred miles on my Prius, but I plan on changing and sampling at 1500miles. Anyone know what type of oil is the Toyota Original fill? I plan on using Motorcraft 5W20 for the first couple short interval changes.

 

<div class='quotetop'>QUOTE(Winston @ Jun 8 2007, 09:29 AM) [snapback]458070[/snapback]</div>

Presumably it is the specified 5W-30. Unfortunately, Jayman doesn't trust what comes from the dealer oil changes (or probably and quicklube type facility), unless he provides the oil himself. With the sodium level I got this time, maybe I shouldn't. I'll will be taking a new sample in 3000 miles to see if there's a change.

Then I guess it's Mobil 1 to be certain whether or not it's coming from a leak or the oil source.

Dave M.

 

I have previously speculated that fuel dilution could be a result of poor PCV valve function. To learn any more, I have to get off my butt and replace the thing.

Before my most recent oil change, I got the engine all hotted up, and left it with the filler cap open. Took the sample as soon as it got down to 'touchable' temperature. This was all I could do to reduce the possibility of 'casual' fuel dilution

Jay, are you on the original PCV, and at what odometer?

 

Would anyone care to interpret this for the non-chemists among us? Could a column be added to the spread sheet saying whether a low or high number is preferred in each row? Or what are the acceptable parameters? I am particularly interested in the one Amsoil 2000 0W30 @ 10,000 miles column, since that is what I use and when I change.

PA P

 

<div class='quotetop'>QUOTE(tochatihu @ Jun 9 2007, 08:10 AM) [snapback]458654[/snapback]</div>

I'd like to know how Jayman and those of you without fuel dilution problems have been making your samples. As I mentioned at one point, for my last sample, I drove at least 20 miles, stopped the car, and took the sample as quickly as I could. The trouble is, the engine isn't really hot. Even with warm weather, the last 2 miles of my drive is under low load, so I don't think the engine temperature was above 160F at the time. Dilution to the point of having a viscosity (of a 5W-30) down to 10 seems unlikely. Maybe I should bite the bullet and change my PCV next week, when I get a chance. I don't think it's supposed to be very difficult to do.

I just did a search through PC on PCV value and found Galaxee's maintenance recommendation list. She mentions that a bad PCV (change recommended at 60k) can result in oil in the intake, but nothing about fuel in the oil. She does indicate it to be an easy job though.

Update: I just found in the manual that a plugged PCV can cause to rich of a mixture. I don't know if it's enough to cause fuel dilution, but it does cause excess CO levels.

Dave M.

 

<div class='quotetop'>QUOTE(tochatihu @ Jun 9 2007, 11:10 AM) [snapback]458654[/snapback]</div>

Yep, original PCV valve, a bit over 78,000 km

<div class='quotetop'>QUOTE(dmckinstry @ Jun 9 2007, 01:09 PM) [snapback]458718[/snapback]</div>

Dave

That could be it right there. It's a bit over 140 km from my condo in Winnipeg to my hobby farm. Once outside Winnipeg, all of it is highway driving at speeds ranging from 100 km/h to 90 km/h. Only the last 4.5 km on the gravel road to the hobby farm is slow, usually 30-40 km/h in the Prius, 50-60 km/h in the FJ.

I currently have around 6,000 km on Mobil 1 0W-30. What I should do is take a sample with the Prius sitting in the condo parking, cold. If there was any issue with fuel dilution, just city driving and sitting should uncover it.

It is odd that even with stop and go driving at -40, I never noticed any fuel dilution. I'm now curious to determine if just city driving causes the dilution

jay

<div class='quotetop'>QUOTE(dmckinstry @ Jun 9 2007, 01:09 PM) [snapback]458718[/snapback]</div>

A plugged PCV valve or clogged PCV tube can also result in rapid sludge formation on the cylnder head. One of the better reasons that car makers went to PCV systems over 30 years ago was to always have positive airflow across the valvetrain, which prevented oil vapor from just sitting there.

With my 1984 Ford F-150, operation in winter - especially in temps colder than -25 C - usually resulted in a frothy, milky buildup on the oil fill and PCV system. I never got more than 2 years out of a PCV valve, so it was a good thing they only cost $5. I then discovered I could clean the PCV valve out with carb spray.

<div class='quotetop'>QUOTE(dmckinstry @ Jun 8 2007, 01:26 PM) [snapback]458130[/snapback]</div>

Any chance of getting a sample of the previous virgin oil? As you may recall, my dealership oil had something like 400 ppm sodium. The two times I've tested Mobil 1 sodium was in the low teens.

 

<div class='quotetop'>QUOTE(maineprius947 @ Dec 20 2006, 07:27 PM) [snapback]364895[/snapback]</div>

Actually this reply is for Jayman.

I replied to you in the other thread about sodium, but would synthetic offset the affects of fuel dilution? Is a viscosity of 10 (with fuel causing it) way too low to be safe for the engine?

Dave M.

 

<div class='quotetop'>QUOTE(dmckinstry @ Jun 11 2007, 11:48 AM) [snapback]459515[/snapback]</div>

Dave

A synthetic is much more resistant to fuel dilution causing viscosity loss, but it's not immune to it.

I'm not sure if you caught the post on my new FJ Cruiser. I had the oil sampled at 2,237 km and it had sheared to 8.0 cSt. I've documented this with the dealership and with Toyota Canada in case I ever have a future issue with that motor.

According to the Mobil specs, fresh Mobil 1 0W-30 has a kinematic at 100 C of 10.3 cSt. Their Mobil 1 10W-30 is rated 10.0 cSt at 100 C.

If I recall, the J300 specs consider 9.5-12.0 cSt the appropriate range for a xW-30 oil

Hope this helps

jay

 

<div class='quotetop'>QUOTE(jayman @ Jun 11 2007, 09:43 AM) [snapback]459547[/snapback]</div>

Thanks for the info.

I'm going to take a sample at ~1000 miles and again at ~3000 miles. If the viscosity is low on that second sample, I'll change early and use Mobil 1.

Dave M.

 

This morning before leaving for work I took an oil sample from the Prius. It has been sitting over a week, was cold, and has been used for city driving only since March. I got the FJ in March and now use it to drive out to the hobby farm.

Once I get the sample report I'll let you know.

 

<div class='quotetop'>QUOTE(jayman @ Jun 10 2007, 07:08 PM) [snapback]459435[/snapback]</div>

I probably can't get a sample from that dealer, but they did tell me it was Mobil (not 1). I may just buy a quart of Mobil 5W-30 from an auto parts place to test that fresh from the can.

Dave M.

 

If they won't let you take a sample, it could be anything. Maybe even re-refined used oil from India, my dealer oil sure made me wonder ...

Go ahead and do a virgin sample of a quart bottle of regular Mobil 5W-30. Then do a sample of your Prius right after an oil change at the dealer. I bet the lab results aren't even close

 

<div class='quotetop'>QUOTE(dmckinstry @ Jun 11 2007, 10:48 AM) [snapback]459515[/snapback]</div>

Dave

I've been away on vacation, but I did receive the oil analysis back. I took the sample cold. As you may recall in a PM I sent you, when I took the sample at the hobby farm, the Prius had already been on the road for about 1.5 hours at highway speeds, which would be plenty of time to burn off any moisture and fuel residual.

The fuel residual was listed at <0.5%

This is clearly a mystery why a handful of Prius have such high fuel dilution. Since I purchased the FJ Cruiser in March to drive out to the hobby farm, I only drive the Prius within Winnipeg city limits, which means speeds of under 70 km/h, stop and go, short trips, etc.

My results may not be typical. I would appreciate hearing back from you if you have anything further to report regarding used oil samples or other issues.