Need info on the "Aunt Millie test"

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Jul 29, 2002
I guess this is sort of on point with this thread? My elderly mother drives about 3,000 miles <i>per year</i>. I've been changing her oil and filter semi-annually. The car is garaged, if that makes any difference? With such few miles on any prospective oil sample, would it even be worth sampling? Would there be any wear numbers on which to make <i>any</i> worthwhile judgements, or would the "dilution-type" analysis numbers be the only numbers that might reveal anything?
I would definitely sample that oil, if for no other reason than curiosity alone! I have been bugging a friend of mine to sample the Mobil 1 10w30 in his supercharged 96 Mustang GT, since he changed the oil last about 2.5 years ago, and only drove about 1200 miles. But he just recently sold the car, and the new owner will be picking it up shortly, so I doubt he'll bother taking that sample now. [Frown] I would've loved to see how it turned out. I often wonder how the time period affects an oil if the car is driven only once a week, but is always fully warmed up and driven hard. Under those conditions, I think things would be different than a car that's driven every single day, but only 1 or 2 miles at a time.
I'm intending to pull a sample of my grandmother's oil from my 93 Olds Ciera 6 at the next 3k interval. She drives about 500 miles per month and is very easy on the car. No short trips, but I am curious. It's 10W30 Pennzoil with an AC filter.
This oil analysis bug really has bit a lot of us hard! I almost feel like one day I'm going to knock on my neighbor's doors and ask them if I can take a sample of their oil too! [Big Grin] For now I've limited it to my own car, my wife's and my mom's. I'd probably sample my father's oil too, but he takes his QX4 to the Infiniti dealer to do it (he brings his own Mobil 1 though)
Patman, The information you want is in SAE Paper #981444, entitled: "Advanced Synthetic Passenger Vehicle Engine Oils for Extended Oil Drain Performance" Presented by Mobil at the 1998 Fuels and Lubricants Meeting of the SAE .... The most interesting thing I found in this paper is that the experimental, 5w-20 and 0w-20 versions of Mobil 1 performed about the same as the 5w-30/5w-40 in terms of wear protection in extended drain testing. TS
Yes, it starts on page 767 of the paper TooSlick mentioned. 1. The aunt minnie test is the test of "the severity on the engine oil during this type of testing is attributed to conditions where the engine rarely reaches optimum operating temperatures." 2. The driving test consists of two short cycles, a 3 mile and 1.5 mile test. 3. "Under this sever driving condition, synthetic oil can provide excellent protection against engine wear and deposit formation." 4. The bulk oil temp ranged from 90 C in the summer to 30 C in the winter. 5. Fuel dilution was as high as 11%. 6. Cleanliness was excellent, the deck sludge rating was 9.7 out of 10. 7. "The iron content showed a low rate of increase, only 100 ppm after 40 months, although there has been a steady increase to over 600 ppm over the last 22 months. The source of iron has not been determined, as visual inspection of the engine did not indicate any abnormal wear or corrosion. In addition, elevated iron levels have not appeared in other test vehicles operating under 'aunt minnie' conditions." The oil was a 5W30 running in a 3.1 L V6 with no oil drains. The oil volume sampled was 5.5L and make-up was 4.4L. TBN retention was 33. Test duration was for 60 months.
There is a discussion on my car club's mailing list about cars that are driven on short trips, and I mentioned the "Aunt Millie" test where they ran that car for 2 years (or more?) doing just very short trips, and all on the same Mobil 1 oil. But I forget all the exact particulars of that test (such as type of car, exact test procedures, etc.) and was wondering if anyone can shed some more light on it for me. Thanks! [Cheers!]
I pulled this much from a post in the analysis section originaly came from Al: (One other thing-probably posted this before. In a 6 year test Mobil ran a 3.1L vehicle 7K miles with 2 very very short trips per day (Aunt Minnie Test) and did not change oil and filter except for topoffs and sampling. At the end of the cycle-even with all the dilutions due to samplings the ppm iron was like 400. And the engine really was judged in good condition and no hint of where the iron was coming from. Go figure.)
Iron is not unusual to see climb in an engine that is used little. The first bit of rust that occurs from the moisture uses up the additives designed to fight it, and once they are gone there is nothing stopping it. That's why I like to get oil out at a max of 6 months, especially in the 1971 Land Cruiser that my father-in-law drives about 2 miles per day divided in 6 trips (worse because he pulled the thermostat and I can't find a replacement).
Patman, You should download the paper off the SAE site: and read the whole thing several times. You will get more useful data then you will from a month of reading posts on this forum .... TooSlick [ October 04, 2002, 08:49 AM: Message edited by: BOBISTHEOILGUY ]
Patman: PM me or email me and I'll send you a hard copy of the material. I will be away today so I won't have time until tomorrow. Al
Originally posted by Al: Patman: PM me or email me and I'll send you a hard copy of the material. I will be away today so I won't have time until tomorrow. Al
Thanks for the offer Al, but MoleKule Fedexed me those documents last week, so I should have them shortly. You guys on here are so awesome!
I got the papers! A very interesting read indeed! It also shows in the tests that the thinner oils like 5w30 and 10w30 show lower wear numbers than the thicker 0w40 and 5w40 oils do! This goes against what a lot of people on here have been saying. It also shows favorable wear numbers for 5w20 and 0w20 oils tested too. This report definitely opened my eyes, as I know the SAE doesn't mess around, I trust their test results (unlike Consumer's Reports!)
Not really, because that engine never got to operating temp. 30C OT in winter! [Eek!] Those thin oils are still MUCH MUCH thicker at that temp than even 20w50 at a normal operating temp. The thinest thing you could get would be best in that situation. 0wt would probably be even better than those! (if you can guarantee it wont ever get up to temp)
There were more tests in that paper than just the Aunt Minnie test though. There were tests on there running long intervals on all types of engines, under all types of conditions, and generally speaking the lower viscosity oils did better at engine wear than the 40wt oils.
Patman, You have to take the tests in context. Also, this was done about 4 years ago and formulations have been tweeked since then. The papers do show how some of the earlier formulations performed; such as the M1 0W40; the Tri-synthetics, 5W40 (Delvac 1), etc, and some future ideas for new formulations. The paper on advanced esters does show their ideas for SuperSyn and the advanced Delvacs. Some of the formulations we may never see, since they are for the European markets.
I a agree with Terry in the Oil Analysis thread regarding the Castrol synthetic. You would think that for a major oil company that Mobil could do at least as well with their formulations as Castrol.
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