Biosyn 0w20 15155 mi OCI 2004 Prius 1.5 l

[dcoyne78]

Analysis by Dyson Analysis, drained enough oil (about .75 qt) so I could add 1 quart at about 10000 miles on Terry's recommendation. Terry rechecked the fuel dilution because of the marked improvement. A new PCV and air filter were installed at about 10k into the oci as well. Results are below, comments welcome.
Code:


Oil Analyses for 2004 Prius

DA=Dyson Analysis, BL= Blackstone

All samples pulled through dipstick, oil changed

9/26/06 @50445 mi, and 6/23/07 @ 65495 mi

Air Filter Toyota OEM

Oil Brand RLI RLI RLI RLI M1 M1

Oil Visc 0w20 0w20 0w20 0w20 0w20 0w20

Oil Filter EaO EaO EaO Mobil 1

Lab______ DA DA DA DA DA BL

Date______ 6/25 1/20 11/5 8/21 6/12

Year______ 2007 2008 2007 2007 2007

Makeup oil* NA 1.125 0.125 0 1

Mi on Eng_ VOA 80650 75496 70601 64456 VOA

Mi on Oil_ 0 15155 10001 5106 14001 0

Aluminum__ 2 5 3 3 8 0

Chromium__ 0 1 0 0 1 0

Iron______ 2 12 8 6 20 1

Copper____ 0 1 1 1 1 0

Lead______ 0 1 0 0 0 0

Tin______ 0 0 0 0 0 0

Molybdenum 8 10 11 161 93

Nickel____ 0 1 0 0 1 0

Manganese_ NT NT NT NT 0

Silver____ 0 0 0 0 0

Titanium__ 0 0 0 0 0

Potassium_ 0 0 0 0 0 1

Boron_____ 11 12 15 63 74

Silicon___ 7 11 20 14 20 3

Sodium____ 11 12 15 13 12 4

Calcium___ 1715 1973 2003 2155 2080

Magnesium_ 12 13 13 27 13

Phosphorus 853 711 829 699 770

Zinc______ 817 1032 1011 1054 871

Barium____ 0 0 0 NT 0

ViscSUS210 NT NT NT NT 54.0

Flashpoint 425 290 370 250 440

Fuel %____ 0 1.55 0.722 1.76

Antifrze % 0 0 0 0

Water %___ NT NT NT 0

Insolubl % NT NT NT 0.3

TBN______ 2.1 2.2 4.2 3.0 9.9

TAN______ 3.42 2.75 2.21 2.4

Visc(cSt100) 8.1 7.5 7.8 8.0

Visc(cSt40) 42.9 39.4 38.5 41.3

Oxidation 162 153 147 25

Nitration 17 16 12 16

H2O(KF-ppm) 512 565 547 505

Soot_____ 0 0 0 0

Visc Index 166 161 177 171

Sulfate Bypr 122 112 113 24

* oil added since previous oil change

 

[Johnny]

That looks pretty darn good to me. What oil are you going to use after the break-in period.

 

[RI_RS4]

Wow, the oil recovered nicely! That extra quart really did a nice job.

 

[buster]

Looks great. I agree, that extra qt must have really helped. The FP is back up to 425F. Does it matter than TAN>TBN? Nice results.

 

[glennc]

Very interesting. If I'm reading it right you're up to about 15k on the oil and still running it? Do you have an intention to change it at any particular mileage (20k?) or will you re-sample around 20k and keep running? TBN is down to 2.1 and the oil appears to have thickened slightly.

Interesting to note that Si has gone down by almost half since the last sampling. Perhaps a little dirt got in the sample last time, or maybe the filter is actually increasing in efficiency and catching smaller particles now. Also interesting but not surprising that Fe is much lower at higher miles than with M1.

I have no idea how to interpret an oxidation number...?

I am curious what Dyson charges for this rather thorough analysis.

 

[badtlc]

$60 according to dysonanalysis.com

 

[benjamming]

buster, I caught that the TAN>TBN at 10k miles and at 15k miles but the oil continues to be in use.

How does fuel go to 0%? I believe this to be impossible. What is the lower limit of the test? That is the highest FP that I can remember coming out of DA.

What oil filter - same one? How are the spark plugs?

 

[JAG]

Originally Posted By: benjamming
How does fuel go to 0%? I believe this to be impossible.

Me too.

 

[RI_RS4]

Originally Posted By: JAG
Originally Posted By: benjamming
How does fuel go to 0%? I believe this to be impossible.

Me too.


Why would that be impossible? If all volatile components of the fuel were able to vaporize and burn off at a faster rate than average fuel influx, then there is no reason why the effects cannot be reversed.

Terry's lab makes two independent measurements of fuel. One using FTIR and the other using closed cup flashpoint. According to the owner of the Prius, Terry had the lab check the fuel number a second time to be sure.

 

[buster]

RI, shouldn't oil consumption go down?

 

[dcoyne78]

Spark plugs were last checked at beginning of oci, they were in excellent condition, but I replaced them anyway (normal interval is 120k for these iridium plugs). Oil filter was the same throughout the oci (an Amsoil EaO 09). I had hoped to continue to 20 or 25k, but the oil and oil filter have been changed (same type of oil and oil filter as before). Possibly a defective PCV was causing fuel dilution and the fuel burned off once this was replaced? I don't really know, but this was the only significant change besides a new air filter (which was also new at the beginning of the oci). In addition, after the PCV replacement the oil level decreased by about .25 quarts, and the car had never burned any oil before, so my guess is the decrease in volume was a gradual evaporation of the fuel in the oil through the PCV. Also when I started the oci (at around 65k) I very carefully filled the oil level to the full mark on the dipstick, but after a few weeks the oil level was about .25 inches above the full mark. On many Prius forums owners complain that the dealer always overfills their oil, but my guess is that by the time they check their oil the fuel dilution has raised the oil level beyond the full mark. The TAN on the virgin oil is not zero and it seems Terry nets out the TAN in the UOA from the TAN in the VOA so that at 10k it was not a problem. Terry also thought the fuel dilution number was unbelievable so it was rechecked and confirmed. Remember that the oil was not consumed, oil was drained so that a quart could be added to refresh the oil ( the .75 quart was an estimate, 4 oz had been removed for the 10k sample). There was very little "oil consumption" until the PCV was replaced and my guess is that fuel was being slowly burned off along with some oil consumption.

 

[RI_RS4]

Originally Posted By: buster
RI, shouldn't oil consumption go down?


It's already pretty low. He drained 3/4 qt to add a quart of biosyn. Total consumption was about 1/3 quart over 15K miles. I'd say that was pretty good.

 

[glennc]

Originally Posted By: dcoyne78
In addition, after the PCV replacement the oil level decreased by about .25 quarts, and the car had never burned any oil before, so my guess is the decrease in volume was a gradual evaporation of the fuel in the oil through the PCV. Also when I started the oci (at around 65k) I very carefully filled the oil level to the full mark on the dipstick, but after a few weeks the oil level was about .25 inches above the full mark. On many Prius forums owners complain that the dealer always overfills their oil, but my guess is that by the time they check their oil the fuel dilution has raised the oil level beyond the full mark.


2% dilution on a 4qt capacity works out to 2.56oz, so unless you are talking about massive dilution then I think some other factor is accounting for the variances in oil level you are seeing. I doubt you could even notice 2.56oz reliably on a dipstick. Or are you talking about fuel dilution in the 5%+ range? That would be different. The highest dilution I saw in your reported results was 1.76% (~2.25oz).

I think many things can cause the observed level to fluctuate somewhat.

 

[JAG]

Originally Posted By: RI_RS4
Originally Posted By: benjamming
How does fuel go to 0%? I believe this to be impossible.

Why would that be impossible? If all volatile components of the fuel were able to vaporize and burn off at a faster rate than average fuel influx, then there is no reason why the effects cannot be reversed.

Dilution can decrease but not go to zero. Fuel evaporation rate from oil is proportional to fuel dilution concentration so the only way for concentration to be zero is for the rate of fuel influx to be zero which is impossible. The PCV valve replacement seems to have made a large improvement in fuel dilution.

 

[RI_RS4]

Originally Posted By: JAG
Originally Posted By: RI_RS4
Originally Posted By: benjamming
How does fuel go to 0%? I believe this to be impossible.

Why would that be impossible? If all volatile components of the fuel were able to vaporize and burn off at a faster rate than average fuel influx, then there is no reason why the effects cannot be reversed.

Dilution can decrease but not go to zero. Fuel evaporation rate from oil is proportional to fuel dilution concentration so the only way for concentration to be zero is for the rate of fuel influx to be zero which is impossible. The PCV valve replacement seems to have made a large improvement in fuel dilution.


JAG, in the limit no measurement of any contaminant can go to zero. However, it surely can within the limits of accuracy of the instruments. Fuel evaporation rate is definitely not proportional to the fuel concentration in the oil. I believe your are confusing rate, which is a derivative, with the actual amount of fuel vaporized. If the fuel influx rate is smaller than the fuel vaporization rate, and both rates are constant, then there will be an asymptotic decrease of fuel dilution to a specific level. (If this level is within the lower measurement limit of the instrument, then as far as the measurement is concerned it's value is zero.)

There are actually multiple mechanisms for fuel evaporation and burn off. I don't know about the Toyota engines, but some engines use cyclonic separators that can be very efficient. And under those multiple mechanisms, the rates are variable. As dilution goes down, it may very well be that the subsequent reduction of aromatic vapor pressure allows the vaporization rate to increase. However, this is pure speculation.

In this engine, I suspect actual fuel influx was decreased to a low level, by maintenance and because of the properties of the oil, and that the operating conditions where such that the vaporization rate was high over this run.

The next UOA sample on this engine will be quite telling. I think that there is more than meets the eye here. Certainly, if these good results continue, there will be something interesting to discuss.

 

[RI_RS4]

Originally Posted By: glennc
Originally Posted By: dcoyne78
In addition, after the PCV replacement the oil level decreased by about .25 quarts, and the car had never burned any oil before, so my guess is the decrease in volume was a gradual evaporation of the fuel in the oil through the PCV. Also when I started the oci (at around 65k) I very carefully filled the oil level to the full mark on the dipstick, but after a few weeks the oil level was about .25 inches above the full mark. On many Prius forums owners complain that the dealer always overfills their oil, but my guess is that by the time they check their oil the fuel dilution has raised the oil level beyond the full mark.


2% dilution on a 4qt capacity works out to 2.56oz, so unless you are talking about massive dilution then I think some other factor is accounting for the variances in oil level you are seeing. I doubt you could even notice 2.56oz reliably on a dipstick. Or are you talking about fuel dilution in the 5%+ range? That would be different. The highest dilution I saw in your reported results was 1.76% (~2.25oz).

I think many things can cause the observed level to fluctuate somewhat.


Don't forget that not all the fuel vaporizes. Non-aromatic garbage is left behind that can also add to the fuel volume. BioSyn also seems to have a property of having higher than usual consumption the first time it encounters a different oil. This tends to reduce and level out, but the oil is definitely designed to have some consumption.

 

[JAG]

Originally Posted By: RI_RS4
Originally Posted By: JAG
Dilution can decrease but not go to zero. Fuel evaporation rate from oil is proportional to fuel dilution concentration so the only way for concentration to be zero is for the rate of fuel influx to be zero which is impossible. The PCV valve replacement seems to have made a large improvement in fuel dilution.

Fuel evaporation rate is definitely not proportional to the fuel concentration in the oil. I believe your are confusing rate, which is a derivative, with the actual amount of fuel vaporized. If the fuel influx rate is smaller than the fuel vaporization rate, and both rates are constant, then there will be an asymptotic decrease of fuel dilution to a specific level. (If this level is within the lower measurement limit of the instrument, then as far as the measurement is concerned it's value is zero.)

"Fuel evaporation rate is definitely not proportional to the fuel concentration in the oil."

Ok, let's put aside the question of the precise truthfulness of the concise statement I made that you disagree with. If there is 0% fuel in motor oil, the evaporation rate of the fuel (not present) is obviously 0 (grams/hour or whatever). If there is 100% fuel in motor oil (not present), the evaporation rate of the fuel is higher than at any fuel concentration less than 100%. How is precisely varies between the two extremes is not important for our purposes (whether it's linear or some non-linear curve). Assuming linearity serves the purpose of explaining how the concentration measurement of 0% is impossible.

I'm not confusing what rate is. Set up the differential equation, use the linear assumption mentioned above that you don't believe, and see what it says. I've already done it.

The measurement yielded a fuel concentration of 0%. There was some present. It went undetected which has been noted which doesn't need to be defended.

 

[glennc]

I suspect that the rate of vaporization undoubtedly relies in a non-trival way on the interaction of multiple variables, not just influx, concentration and vapor pressure but also the vaporization energy available (heat, direct radiation), boundary surface areas and of course the precise chemical qualities of the contaminating fuel.

Eventually you will reach an equilibrium level of dilution for a given set of operating conditions, and I think that the question really has to do with how quickly the dilution rate will vary to approach that equilibrium in practice rather than the exact theoretical rate of change under a simple set of static assumptions.

We know empirically as well as theoretically that highway driving and longer trips will tend to lead to an equilibrium at a lower percentage of fuel dilution and winter driving and shorter trips will do the opposite. It seems to me that the actual rate of change can often be fairly high and that fuel dilution could go from high to near zero, or effectively to zero, easily between sampling intervals, and could even have oscillated between high and low values multiple times in such a period.

I could be missing something, of course....

 

[glennc]

Originally Posted By: RI_RS4

Don't forget that not all the fuel vaporizes. Non-aromatic garbage is left behind that can also add to the fuel volume. BioSyn also seems to have a property of having higher than usual consumption the first time it encounters a different oil. This tends to reduce and level out, but the oil is definitely designed to have some consumption.


Is that non-aromatic garbage measured by the lab as fuel dilution? If so then it would be included in that 1.76% (or whatever) reading and also in the 2.25oz (or whatever). If not, and if you are saying that more (much more) than 2.25oz could build up over time and yet NOT be measured by the lab as fuel dilution, then it seems the fuel dilution test is not very useful.

As for that non-aromatic garbage in the first place, if fuel dilution is the result only of the condensation of crankcase vapors, then could the resulting dilution not re-vaporize fully?

If on the other hand it is partly the result of actual fluid fuel entering the crankcase and diluting the oil then it would make sense that some proportion of it would not vaporize at typical crankcase temperatures.

But how do you decide, other than guessing by the amount of dilution present, whether it is entirely from vapors or whether it is partly the result of actual fluid fuel leakage?

 

[dcoyne78]

Glenn, you are correct, if the fuel dilution was 2 % it would only add about 2.5 oz to the oil volume and the oil level was down 1/2 quart after the 4 oz sample was pulled, so 6.5 of the 16 oz is accounted for and the rest was consumption or possibly some portion may have been water that was driven out as well (speculation on my part). If there was no change in moisture content then I consumed about 9 oz of oil over the last 5k which is not unusual. Mostly when I used to do 5k ocis I would burn about 1/4 to 1/2 quart over the interval, I never needed to add any oil.