Fuel Dilution of Engine Oil

I don't need a UOA on my oil to tell if I have fuel dilution issues. The dipstick is quite stinky. I smell fuel.
Research on this site has lead me to a possible motor break in error. I changed my oil out at 1000 miles to Mobil One. Fresh Mobil One 5-30 every 5K since. Now at 16K. I drive real easy on the car. I have since read many articles on different approaches to break-in especially running the car real hard initially to seat the piston rings. I don't believe in that procedure but this is the first new car I can smell fuel in the oil so maybe there's something to that procedure concerning this car. It runs perfect no smoke at all but the oil stinks.
The only place fuel can get into the oil is through the piston rings.At 16K
my lifetime is 47.8 so its not hemorrhaging but there's fuel there. AS a side note I see a pool of oil in the bottom of the intake too when I look into the TB with the throttle open.
I have my 1000 mile oil sample and a 5K CVT fluid sample and a 10K RedLine CVT fluid sample sitting in my garage just waiting for the next time I go to Orlando as PDF is on the way. About 30 miles from my house. I will report my tests when I get them done. But I got fuel for sure.

 

Speaking of reliability of older vehicles, my Toyota Crown turned 40 this year and is still running. I replaced the fuel pump, and the brakes have been rebuilt, that's it.

 

Hi Ed,

Wow, if you can smell unburned fuel that is not good. I can smell HC in the used oil, but this is the same smell as with any other car.

In the past I recall the conventional wisdom was to use mineral oil at least for the first 12-15K miles to facilitate the engine break-in process. Have you considered switching to mineral oil for that period of time, then returning to synthetic oil after that additional mileage has been logged?

Regarding the pool of liquid that you see in the intake manifold, it could be engine oil but my current hypothesis is that it is unburned fuel that came up from the intake manifold. This is because the color of the liquid seems to be lighter than used engine oil.

I don't see a pool of liquid in my car (instead, the bottom of the intake manifold is moist). My theory about that is owners who see the pool probably drive very moderately and have the throttle only slightly open most of the time, so the liquid pool has a chance to form with less air flow passing through.

 

Hi Patrick,

Maybe its just HC I'm smelling. Really strong HC.

Yes I drive moderately and it appears to be oil in the bottom of the intake. Its quite dark. I will see if I can grab some of it to check. Whats confusing me on the dipstick smell is there's a lady at work who bought a Prius last year the same week I did. The other day I asked her if I could "look" under the hood at something for a second. I smelled her oil.....she must think I'm nuts...but her 07 car smells just as bad as mine.And she has been on dino oil for 20K. So maybe it is just HC.
I then checked my 50K Ford truck and it does not smell as bad. So
I must get the oil UOA'ed real soon.
Again my average lately is 47.8 so I'm not hemoraging but I know fuel in the oil is not good. Thanks.

 

Without a used oil analysis, it would be impossible to determine if the oil has fuel residue. Just going by color or smell is iffy, at best

 

you can't smell unburned fuel in the oil. some oil just smells like that. at 1%, there's no way you would smell it.

DH doesn't like to stick his nose in the UOA threads, just his personal feelings on the issue, but he's gonna give this input:

his greasecar engine oil smells like wvo after 2500 miles. smells strongly like it. the engine leaks like a sieve, oil level never changes regardless of that, and he refuses to do yet another engine rebuild in what nonexistent spare time he has. he would gladly take a 1% fuel dilution at 8300 miles!

in his view, it might be better to change at 5k intervals, but of course it's your call and your car. blowby happens, especially with the higher compression.

now. on to the whole longevity of the vehicle argument.

you don't see many 1988 supras around because they didn't make many, and lots of those got smashed into trees by the typical class of owner they attracted. ask the same question with a 1988 camry, and the answer will be very, very different. we have owned 4 of them now, you can't take a trip to the store without seeing at least 2 of them, and you can't KILL the damn things (well, unless some raving drunk rams your trunk into your backseat for you at 3am.)

electronics failure mode analysis is not like mechanicals. mechanicals will see an increasing failure rate over time- the more they are used, the more likely they are to wear out. electronics have a random distribution. that is to say, normally the electronics are as likely to fail today as they are 10 years from now. toyota's connectors are pretty good, and design has only improved over the years.

wiring degradation is not specific to the prius. the old 2g camrys that we have owned had little wiring degradation at ~20 years, the big weak points were the flex points (door and trunk wiring harnesses) but the wiring itself just falling apart after x years isn't a problem. plastic looms may shatter with age, but the wiring inside is fine.

jayman, your problem is 4 letters: ford. even when DH was fixing cars up north he did not see too many problems with older toyota vehicles' wiring. our very first camry saw ~250k miles in wisconsin salt, the side markers eventually rusted out of the vehicle body and were hanging on by the wires, still lit up though!

the prius will last a long time, we're not too worried about that.

 

Ditto on that about the Ford. They have horrible wiring in my experience, and the ignition system was complete crap. When I had an F-150 I changed plug wires as often as I changed the oil. It would run very smoothly for a few months...then it needed wires again as there was a progressive hitch in the idle...then power loss...etc. I rebuilt various parts of the system hoping to excorcise the demons, but it never did any long term good.

Ford also put the wrong material in the connector for the alternator harness. It couldn't stand the engine heat and was failing...didn't realize it until I tried to pull the alternator, the plastic clips broke off in my hands as soon as I touched them. The alternator also failed at night, literally 45 minutes back over a couple of mountains on a large west Texas ranch. I did manage to get it back out by shutting off the lights and using the stars (no moon) and reving the hell out of it until the alternator feebly kicked in. I considered getting out and emptying a clip into it...as I was approaching the last straw with it. At any rate when I went to change the alternator is when I learned about the alternator harness issue...the new alternator had special instructions and parts for soldering in a new one because the old one was a fire hazard.

Then there were the cracked exhaust manifolds on both sides...idiotic cantilever design that was just begging to fail. And the grommet on the accelerator that failed and forced me to beg tools along the road so I could get the blasted thing running again.

The only thing that F-150 reliably did was p*** me off.

 

Not quite. At least with military electronics, when you apply FMECA (Failure Mode Effect Criticality Analysis), FRACAS (Failure Reporting And Corrective Action System), and DMECA (Damage Mode Effect Criticality Analysis), there are interesting trends.

Especially with FIT (Failure In Time). FIT is used to help determine MTBF

For example, for any given lot of something, say EMP hardened power modules, you can expect a certain level of "infant" mortality. Very critical systems have the component parts subjected to extended burn-in, to weed out the infant mortality. That is a very expensive process, however

Overall, it can be iffy to determine MTBF when you factor in things like voltage and temperature excursions. For example, a voltage spike may not destroy the component, but in the near future the component may start latching up, or outright fail

These are interesting articles on FIT and MTBF

http://www.tamiu.edu/~tjin/publication/rams2007.pdf

Embedded.com - Using MTBF to Analyze Bus Reliability

8.2.2.3. Trend and growth plotting (Duane plots)

Of course, over time there are chemical changes to electronic components. Electrolytic capacitors can leak and or dry out, and fail. Repeated thermal cycling can cause microscoptic solder voids to suddenly cause a poor connection

One truth of mechanical devices and electronic devices: as total elapsed time increases, the potential for failure also increases

Yes, I'd agree that Ford really pushed the "cheap s***" concept when they built their wiring harnesses. However, all wiring harnesses degrade with time.

A good example of this, would be all the airliners parked in the desert in California and Arizona. Although still having mechanical life left, the wiring became dangerously unreliable. This is in large part due to the use of Kapton wire insulation, which is now illegal to use in critical aircraft wire looms

Kapton can crack under certain conditions, and once a short happens, Kapton will turn into a conductor instead of an insulator. Rapid total destruction of the wire loom results, usually with fatal consequences. Eg: total loss of vehicle, mission, and crew.

Since wire looms are built with aircraft sections, before they are joined, it's almost impossible to simply "rewire" an airliner. You would literally have to take it apart at the factory "fuse" sections, and the cost of that means a 15-20 year old airliner is better retired than fixed

Imagine the PITA of rewiring a house, which I have done. At least in my case, I felt like just throwing a match to it. The wire from the early 1960's was literally falling apart, and very dangerous

Near Mojave Airport, California, the Flightline 1434 area is filled with "retired" civillian and military aircraft. Near Tucson, Arizona, the Davis-Monthan Air Force Base also has a collection of such retired aircraft

I have no doubt that in 10-20 years , we won't see too many modern cars still operating. As the wire degrades, resistance values will change. Consider how picky sensors like crank, cam, throttle position, O2, MAF, etc are to even slight wiring damage

The best example I have seen was after the mices have nibbled on wiring harnesses. The harness wasn't severed, just nibbled on, and that is usually enough for the "Christmas tree" on the dash, and/or a no-start

 

If you want to watch a scary test of Kapton causing arc tracking, check out this link

NewsChannel 5.com - Nashville, Tennessee - Which Aircraft Have Kapton Wiring, and What's the Problem?

The links to the videos are near the top left of the report. It's a good thing those airliners are parked in the desert. They may be almost mechanically pristine, but dangerous to operate

The test was done by making a very minor nick in the harness, then allowing water to slowly drip. Something you might expect under an airliner lavatory

 

j-

you bring up some good points. DH's main point is that electronics do not have the same very steep failure-probability vs time curve that you see with mechanicals. blaming the increased electronic complexity of the prius for its supposed early death is going a bit far.

tolerances are tighter now, and that could take out some vehicles. and it could be that modern vehicles won't last as long, but DH is more optimistic than others in this thread.

 

I'm very optimistic that my car will last as long as replacement parts are available for it.

 

N

Correct, overall you won't see such a slope. However, you can also venture "off the chart" or into a gray area, by not comparing true "apples to apples"

As an example: a typical mass-production vehicle cannot be compared in reliability (MTBF, MTTR, FIT) using Weibull, ANOVA, FRACAS, etc, to individual semiconductor items

At a certain level, it should be obvious that the reliability of a SYSTEM can only be as high as the *least* reliable component. With proper engineering, one can try to minimize single mode failures such that the least reliable component doesn't cause a fatal sequence

Even comparing what may appear to be similar mechanical systems, has iffy results. A lot of folks assume a motor is a motor, is a motor. Right? For the most part, Toyota makes reliable motors, with some famous examples that may or may not have been caused by extended oil changes with cheap North American crap oil

Would it be fair to compare a large industrial "prime mover" motor, to a car motor? Around 50-60 years ago, a company called Nordberg made large Prime Mover motors. Eg, V-10, V-16, V-20, even a unique radial 12 Prime Mover, ranging up to around 5,000 hp.

These motors were built to last - literally - for generations. Here is a photo of a "dual fuel" radial 12, see attachment. Nordberg was based in Milwaukee. They disappeared around 30 years ago, due to no longer having a market for very large, long lasting motors. However, the motors are still in use

Even modern Prime Mover motors, such as Waukesha (Made in Wisconsin), or Wartsilla (Made in Helsinki, Finland) will offer MTBF many, many times in excess of a typical car motor. That is to be expected, these engines typically cost several hundred thousand dollars, upwards of low millions, and power critical loads

As far as the Prius long-term reliability, I didn't mean to suggest it would have *lower* reliability than a modern vehicle. All modern vehicles, with complex arrays of sensors, will be subject to the same wire ageing issues.

J

 

he was referring not so much to vehicle mechanicals vs vehicle electronics, he was trying to point out the failure rate of electronics is not like mechanicals in that the older mechanicals are going to fail simply out of wear-out issues. electronics don't wear out from use. though weaker components will express themselves frequently enough to be identified as such in a large sample.

the wiring as a whole will probably last. again, even up north in salty, nasty conditions the body will rust out on 20-year-old toyotas before the wiring goes. he spent ~4 years working on southern cars since we came down here, with the fairly intense heat in the summertime, he hasn't seen wires just falling apart on 20-year-old toyotas (and even some reaching back to the 1970s model years).

your point about the weakest link is absolutely true. but electronically, those same older toyotas also had engine and auto transmission, door, seatbelt, cruise control, a/c amplifier ETC ecu's that, again, haven't failed in droves either.

he's pulled wiring harnesses out of newer vehicles, which are still put together with high quality wires. combine that with what he's already seen in older toyotas and he'll just leave it at "like always, time will tell"

 

I would be highly surprised if the MFD didn't fail at a very high rate after 10 years.

The number of ECU's is also a concern. I don't know how many capacitors or connections we are talking about, but over time I've had a number of such things fail in PC's. Likewise, I've had memory chips work well for a year or so, then show signs of intermittent or complete failure. This is the first vehicle I've owned with even close to this many ECU's.

There is a fair chance that salvage parts will be available for most of these issues, but a weak link is likely to appear and the salvage parts for that will dry up. (MFD is my guess.)

 

The Classic population is only 5-7 years old, and already it is pretty clear that the following systems are vulnerable to early failure (see my poll here: http://priuschat.com/forums/generation-1-prius-discussion/45766-classic-prius-repairs.html )

- electric steering gear
- traction battery
- engine and hybrid vehicle ECUs
- inverter
- the fancy catalytic converter with HCAC valve

Suppose you own one of these Classics, you have 150K miles on the odometer, and the market value is $7K. 2001 Toyota Prius - Private Party Pricing Report - Official Kelley Blue Book Site=

Also suppose you are not a top Prius mechanic and you have to rely on Toyota dealer service. You start to experience failures of the systems listed above. How long are you going to be willing to put $$$$ into a car that is only worth $7K?

I think that Classic owners with a 150K+ mile odometer reading who spend $3-4K on a new battery (plus dealer tech labor) are crazy - since there's no assurance that they are done with respect to future repairs...

 

the first iteration of a new model tends to have a lot of issues. the classic prius was a... learning experience. DH agrees that owners of high-mileage classic prius shouldn't sink too much cash into the car. the money would be better spent on upgrading to a newer car.

 

All this trash talk on the 2001-2003 Prius pleases me - it means that I should have access to them at friendly prices. So keep it up!

The availability of new (too expensive!) parts will eventually fail, and then one would have to depend on vehicles crashed out of the fleet. Overall I suppose that more than a few can be kept roadworthy by interested parties. I just drove the old rig 70 ish miles and it's still pleasing. A bit noisier than the newer model as is well known.

I happen to expect some to long outlast the wide availability of gasoline-like fuels to propel them, but that is another matter.

 

Well, actually yes, they do. It's just that the curve from such lot numbers of components have nothing in common with typical mechanical Weibull or FIT analysis. Otherwise, there would be no need to "guesstimate" MTBF for solid-state components

As an example, consider DC-to-DC power modules commonly used in industrial and military applications. The early lot numbers of a certain brand were subject to substrate delamination from the thermal cycling. This had nothing to do with overheating, just "normal" temps

Another issue that became apparent would be certain void issues in solder connections. If you have a subscription to this site, you'll find this article fascinating

Cookies Required

There is also the concept of "thermal aging" which tends to effect the newer lead-free solder systems. This was poorly understood until recently. This article does not require a subscription, and has nice graphs and SEM's

http://www.smta.org/files/dallas_TI_voids_presentation.pdf

Keep in mind that technology that we thought was "stable" 20 years ago, is now proven unstable or having a far lower MTBF than orginally predicted

Early infant mortality is predictive of actual manufacturing defects. Even if lot numbers predict a certain MTBF range, that range usually assumes degraded performance

Eg: 100,000 hour MTBF, with end-of-life 50% expressing degraded performance, increased resistance, decreased thermal excursion resistance, etc

If high quality wire and insulation is used, probably yes. If very min-spec Ford crap is used, probably not. Up here, if a 20 year old Ford or Dodge is still running, the wiring is literally falling apart and not worth fixing. Unless you're a Mad Scientist and need something to keep busy

Oh I do not know, that 1990 4Runner of mine, the combination switch for the front and rear wiper went kaput in the late 1990's. The front wipers no longer worked. I had the shop manual, took apart the steering column, swapped the connectors for the front and rear wipers, and got the front wipers going again

If you really want to see a WEAK link in a vehicle, the ignition switch in millions of older Ford pickups. From the steering column, a rod went down to the switch in the dash.

The actual switch could short out and make the vehicle burst into flames. Much like the more recent problem with Ford cruise control brake sense switches, they would also make the vehicle burst into flames

I doubt a Toyota would behave like that

 

There is also ion migration in semiconductors, and while the MTBF is long, when you combine a large number of semiconductors in a system the odds of failure becomes fairly high.

A good example are LED Christmas lights. The LEDs in Christmas lights have a long MTBF, but if you run seven strings of 60 lights each 24/7 you will get around three failures a week. Statistics have a way of sneaking up on you like that.

Tom

 

Or in certain high energy radar systems, who would have thought there would be weird corrosion problems with certain waveguide assemblies?