Tegger's real-world oil consumption

On 5/28/2010 7:13 PM Tegger spake these words of knowledge:

It's of interest to me; over this time frame, you averaged about 1660 miles per quart of oil. That's not bad, given the wear on your engine. A lot of work, and good information. And something the rest of us can measure oil consumption against.

I wish there were more folks doing this level of information-gathering.

Thanks, Tegger.

RFT!!! Dave Kelsen

On May 28, 6:13=A0pm, Tegger wrote: snip for brevity

I think the above represents a well-done study.

I too would think that oil consumption would be pretty consistent over the 41k miles. But taking into account errors in measurement, consumption perhaps is pretty consistent. For example, using the chart linked above, the reader can surmise that the average consumption was about 1660 miles per quart (mpq) with a range from 1500 to 1850 mpq, or +/- about 10%. Reading error for each measurement taken would maybe be around 0.04 quart ( =3D about one-half a gradation =3D about one-half mm on the calibration chart next to which you held the dipstick). Temperature effects might cause an error in reading of around +/- 0.03 quart (=3D .0005 per degree F * 20 degree F * 3 quarts). You monitored every 1k miles or so, so I gather you did two readings of the dipstick per data point. Each reading could be off by 0.07 quart. Hence any given data point might be off by around 2*(.04+.03) quart =3D 0.14 quart or around 10% error, consistent with what your readings were. Hence I would say the variation you found might be explained by the measurement error involved in doing readings. Hence the average number you found is useful.

I see from the "Bob is the Oil Guy" (BITOG) thread you used Mobil 1, a synthetic oil, for the entire study. I think this may be relevant for some readers. E.g. those who are still using non-synthetic oil might expect higher oil consumption for an engine the same age as your Acura's.

(Anyone wanting to see Tegger's thread at BITOG should just do a BITOG keyword search for "Tegger.")

Elle wrote in news:58d793a8-b69b-445a-ad69- snipped-for-privacy@y12g2000vbg.googlegroups.com:

I'm a bit surprised that nobody in BITOG has brought up this extremely important point. I was fully expecting to be called-out on reading errors, but nobody's done that yet except you.

As you point out, the obvious uncontrolled variable here is my dipstick- level-recording method: It's a simple visual comparison between dipstick and chart, which is subject to some guesswork as to the exact position of the "meniscus".

Of course, the level doesn't go in increments that match the markings on my chart, but is usually in between the marks. Is it closer to one mark than the other? Do I call it 6.3? 6.4? It takes very little change in what I record to make a big difference in the final mileage number. That's part of the reason I need very many records in the dataset; it's the only way of materially reducing the inevitable contamination caused by reading errors.

I take at least four readings each time I do my readings, just to be certain I'm reading the level correctly. Even then there is some "fudge", since the oil runs down the stick fairly quickly, especially in warmer weather. I need to make sure I check the level quickly, before the level at the "meniscus" thins-out so far that I have difficulty locating the top of the "meniscus".

I had been using M1 for some time before my decision to keep precise records, and kept using it just to eliminate a variable.

I have, though, also discovered that M1, over more than 100,000 miles, produces FAR less varnish than Castrol GTX did over the same mileage. I've been sufficiently impressed with M1 that I wish to keep using it.

Dave Kelsen wrote in news:4c011d2c$0$15235$ snipped-for-privacy@unlimited.newshosting.com:

You're welcome. The testing continues apace. An update will be issued at some point in the future, once more records are generated.

I don't know why you're changing oil every 3K. Any reputable oil such as Castrol, Valvoline etc should be good for at least 5K.

JT

What kind of lap times do you think Helen Keller could achieve on the BBC TV show 'Top Gear'?

Hi, I am not sure what you mean by "called-out," but I want to be clear that I was not trying to criticize your work. Rather I was curious about the variation and whether it might be explained by measurement error. I think the variation is not meaningful and is to be expected. Your study is /extremely/ well done. I doubt any other DIY-er could get a narrower range for measured oil consumption. Your study is instructive in a few ways, in fact.

I guess I might also keep in mind that generally, oil consumption is going to rise. As you know. So one cannot take an average of too long a time period and have it be meaningful. Rather something like the average over every 50k miles seems like it would be helpful to folks as a measure perhaps of how much wear the engine is seeing.

Do you mind if I post a link to your chart and a summary of it at honda-tech.com ?

snip for brevity

Yes, I understand: Lots of data points help average out any measurement error.

snipped-for-privacy@FreeNet.Carleton.CA (M.A. Stewart) wrote in news:hu19ht$ct1$ snipped-for-privacy@theodyn.ncf.ca:

They once actually did have a blind man in their "reasonably priced car". He'd lost his sight in a bomb-blast in some Third World country when he was with the British military.

Jeremy Clarkson and he did /many/ test laps during which (with "Jezza" as passenger) they'd worked out a rally-type system with Jeremy as navigator.

The blind guy did not finish last.

Elle wrote in news: snipped-for-privacy@u7g2000vbq.googlegroups.com:

By "called-out", I meant I expected somebody to bring up the issue of measurement accuracy when reading off the dipstick. The entire work depends on that, of course. And nobody but you brought it up. That doesn't say much for BITOG, frankly.

I'm complimenting you, is ultimately what I meant.

That is very possible. I considered the possibility myself, but had no real way of compensating for it outside of large sample size.

I'm no statistician, but I've done enough testing and offhand statistical analysis--both personally and as part of my job--to realize that variability is the norm in statistics, and can be very difficult to both account for, and to correct for, when attempting to determine trends and tendencies within the numbers.

I'm not totally sure what accounts for the variation. As you point out, it may well have to do simply with the vagaries of my vision and with my judgments as to the exact fractional positioning of a particular reading.

I found that if I considered a reading as being 0.1 of a mark higher or lower, that made as much as 500 miles per quart difference in the final analysis. I had no way of correcting for that other than sample size. When calculating gas mileage, one faces the very same variability problem.

My reading-records were conservative, normally erring on the side of higher consumption. IOW, if I wasn't quite sure, I'd guess on the higher side (6.4 usage versus 6.3, etc.).

If what I'm seeing is accurate, I believe consumption rises very slowly over the years. I believe that the reason some people see a sudden large hike in usage is because they never check their oil. And then one day they do, and it's a LOT lower than they expected. They conclude from this that it all-of-a-sudden started happening.

Please do. When posting to BITOG, I was hoping for somebody to chime in with meaningful technical criticism and advice. So far, you're the only one. Maybe we can get others in hondatech.

Hey, you're doing peer-review! Cool!

Lots of data points = large sample size.

dude, with the greatest of respect, and don't take my pedantry personally, but there are a number of things here which are really bad practice and a correspondingly bad example for other users.

1. you're dipping the oil too long after shutdown. you should be following the procedure honda specify - "a couple of minutes after shutting the engine off". it is the only consistent method available to all users, all conditions. you are an adherent of the owners manual after all...
2. your change intervals for the oil you're using is way too short. i can see a shorter interval if you're trying to de-gum an engine that's been abused, but here, you're wasting both money and resources. if you want to spend the money on something useful, spend it on analysis, not wasting oil.
3. don't over-think this meniscus thing. all you need to do is ensure consistency. if you're serious about making quantitative measurements [as opposed to monitoring trends - the real objective here], install a sight tube and vernier. and make sure you take thermal expansion into account. see #2.
4. again re #2., you should allow for batch differences in the base oils. mobil /do/ use a proportion of group III in their base, and that proportion varies from batch to batch. it stands to reason that the gIII's greater propensity to breakdown will give you variance in consumption levels in line with content proportions. what you should do is stick to a longer interval and you'll find that the aggregate total over the full cycle is more consistent. the rate of consumption drops as the volatiles burn off, so this will have a better averaging effect that is more consistent with your vehicle's consumption over the use cycle, not reflecting the oil's composition and initial burn-off rates. [you can also try mobil's eco or extended performance blends - a lower proportion of gIII's and in my experience, lower oil consumption.]

indeed. he's using mobil 1 - he should be looking at 10k at least.

oops, forgot to mention:

among other reasons, oil temperature and whether or not the oil filter's anti-drain-back valve is functioning are factors here. dipping at full working temperature is consistent. dipping before drain-back happens is consistent. anything else is subject to considerable variance.

I'm sure he beat Al. :)

On 6/1/2010 9:21 PM jim beam spake these words of knowledge:

Checking your oil every day before the engine is started is consistent, and tells you how much oil you have in your system. As Tegger pointed out, you want to do it while the car is in the same physical location as well, to eliminate vagaries of level.

RFT!!! Dave Kelsen

consistently wrong. for the reasons stated above, it needs to be checked after the engine has attained full working temperature and has been shut down for "a couple of minutes". like when you've pumped gas. all gas forecourts are level. just dip the oil when you fill up. like it says in the honda manual.

no, dipping when cold doesn't. it doesn't allow for temperature differences, and it doesn't allow for filter drain - i.e. whether or not the anti drain-back valve is functioning. filters are very inconsistent in that - tegger should know - he's written about it before.

again, the only consistent and accurate method is to dip as above. after all, it's where the dip stick marks are positioned to be read - there is always a difference between hot and cold, and honda are positioned to be read hot.

I have only seen a few of the shows. But I do remember briefly seeing on the tower of lap times, close to the bottom (and above a few others... poor folks), the pasted-on 'Blind Man' lap times. I didn't believe it at first... but later I saw it again, and thought it was a riot (a politically incorrect riot of course). I had assumed that they had possibly blindfolded a person to get the lap times.

So do you think Helen Keller could turn better lap times than the 'poor folks' below the Blind Man (hypothetically)? What about Patty Duke? Could she turn better lap times?

Your whole PDF is almost too utterly ridiculous to even comment. Your explanation of your methodology is rather confused. You claim to take measurements every 1000 miles which doesn't jive with the mileage numbers shown on the chart. You cover period of 41000 miles. That should mean (if you took a reading every 1000 miles) 42 measurements, but your chart only shows the result of 17 measurements. So what about the other 25 measurements that should be there but you don't show? The 17 points on the chart don't show data they show some dubious calculation you made from whatever data might have been. The data itself is probably also dubious. You may have a mark on your dipstick when the sump is full and a mark when the oil is down a quart, but that doesn't mean that half way between those 2 marks is where it is where it is at half a quart low. This would be due to the irregular shape of the oil pan.

Using your method is like using the gas gauge to calculate gas mileage. With that type of bogus measuring someone might conclude: Gee for some reason I always get 40 mpg on from full to half a tank and then get 20 mpg on the second half of the tank. All you have really proved is that with the first reading of the dipstick you get some reading plus or minus one notch on the scale. And with the second reading you get plus or minus some other notch on the scale. You consistently get to around some point on the dipstick at 1000 miles and consistently get to around some other point at 2000 miles. And that is about all you can say conclusively.

Here is what it looks like to me.

2) After 1000 miles you infer from your flawed measuring system that it has used about .65 quarts at that point which means it went 1540 miles/qt. In reality the engine has really only used .5 quarts at that point in the cycle which means it has really gone 2000 mi./qt.

4) At 3000 miles your chart indicates you don't do any measuring/recording data you just change the oil and repeat the foolishness from step 1).

The fact that you repeat the same bogus methodology over and over and get somewhat the same results repeatedly - you interpret as being meaningful.

That appears to be obvious. You're Not much good at accurately collecting or reporting meaningful data either.

-jim

The chart says near the bottom: "Not all 1,000 mile intervals were recorded (some were missed for various reasons)." This happens in experiments all the time. When it does, the question is: Are there still enough sample points for statistical meaning? IMO, yes.

Tegger stated at the BITOG site that after "the first level check I top it back up. Then I top it back up after the second check. At each check-time it's down a bit more than a pint, depending."

Hence before he adds oil each time, he must be reading near the same point on the dipstick each time. He might be a little off, but given he knows how much he adds to bring the level to full, I doubt he is far off. Given how often oil checking is discussed here, it would not surprise me if he checked for linearity on his Integra's dipstick. Some dipsticks apparently are pretty linear from low to full. Not all, but some. At any rate, give him a chance to answer.

Someone at honda-tech.com suggested he instead measure how much oil is needed to bring the level back to the full mark. Presumably he is adding oil very carefully to top off the level, and so the volume could be measured.

That doesn't even begin to answer my question. Why is most of the data missing? Why isn't there any data for how much was used between 2000 and 3000 miles? If there was any serious attempt at accuracy, there could have been an accurate accounting of the total consumption for the entire oil change interval plus an accurate accounting of how much was added along the way. This doesn't even begin to look like a credible study.

Well that is a rather important detail to suddenly introduce after the methodology has been questioned. So what is all this nonsense about measuring ticks on the dipstick? Why not accurately measure the amount added to get it back to the known full level?

If he does know that actual amount added to get it back to full, why would the calculations be made from the dipstick readings? It makes no sense at all.

I'm a little suspicious of anyone who leaves out the most important details and then when the deficiency is noted they suddenly come up with a story. If they understood the importance from the beginning then why would they have not mentioned it from the beginning. The most important detail that is excluded is why does this study look like it is just cherry picked data. I can see no good excuse why all the data was not included. Nor is there any reason to believe that the 40% of the data that was given is representative of what all the data would have shown if it had been collected and reported using credible methodology.