Double-Super-Secret 5W-40 Audi RS4 Racing Oil

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The following is a wear plot for an Audi RS4 engine over a period of 18K miles, with samples taken at 3K oil intervals. This engine has proven to be a bear on oils, because of chemical shear, due to high fuel dilution of the Direct Injection, combined with the mechanical shear of an 8250 rpm racing V8. Oil in this engine has been shown to have about a 3000 mile or less life expectancy.

So, about a year ago I enlisted the consulting services of the esteemed Terry Dyson, to figure this puppy out, and formulate a best oil solution for this beast. Prior to the experimental test oil, Elf Excellium LDX 5W-40 and Motul Etech 0W-40 were used in this engine, with poor results. Other RS4 owners (10 in total) have participated in subsequent monitoring and testing of different Audi-approved 502.00 oils. After studying the problem and performing some focused testing over the past year, Terry has worked with a formulator on my behalf to design an oil to solve these problems.

The initial 3000 mile testing on the Double-Super-Secret Experimental Racing Oil is complete. The stuff that Terry Dyson designed for the RS4 engine and had formulated works. All wear numbers are down to lowest levels ever recorded in an RS4.

Sample points are shown. The curves are Excel fits to the points.

Flashpoint is up to 320F, from a recorded low of 235F in my engine.

Fuel dilution is down to 1.29%, from a high of 2.37%.

Viscosities are highest recorded for 5W-40 Oil in an RS4

100C cSt - 13.3 (low 40W)
40C cSt - 76.6 (high 20W)

These measurements include two track days at Watkins Glen at sustained high rpms.

I'm sure that Terry will entertain answering questions in due time.

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Can you reveal the formulator? I already have an idea. LOL

Looks like things are going in the right direction.
 
It was through BITOG that I sought Terry out. First to do premium analysis, and then to try to figure out how to fix what was broke. In this case, Audi FSI engines may have an Achilles heal that can be mended with the right oil and chemistry. This is just a step in the formulation process. Some additional oil "tuning" will most likely be undertaken to tweak the performance. And although this oil was specifically formulated for the RS4 V8, it may very well be applicable to solving problems in many different FSI and DI engines on the market, that are experiencing fuel dilution.
 
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Did it take 6k miles to break in the engine?




Yep, that's about right. Somewhere between 6 and 8K miles according to the wear data on 10 different engines. The block is Alusil, a high silicon aluminum. The cylinder walls are bored, honed and then chemically etched to remove the aluminum, leaving silicon (glass) exposed. The cylinders are then lightly honed and polished, leaving a glass-like bore. The pistons use thin, light, low-tension racing rings, so it takes quite a while for those puppies to lap in.
 
the oil may be great and all, but you just barely got 100% out of your breakin phase. It has been stated many a time that UOA is not even all that useful until you hit a baseline in your UOA results for which to improve on. You were still in a transient range due to breakin.

If we look at dW/dt, we only see a maxima by convenience, excel does a nice job of smoothing fit curves between points for it to look like things were at steady state, but do we really know???

I'd suggest you use a polynomial trendline on the first three points, and extrapolate from there, over your whle mileage range, to determine where your actual approximate breakin point is, and how different the data shown is from the standard trend of how the UOAs were reporting (youll need a fit with x^2 dependence, but this will be parabolic in nature, and will behave just as youve shown the data to behave within the locality of your testing range). From there, one would have to subtract out oil performance factors (the motul is odd, because it has the highest wear as one of its points, but then it drops significantly in the second point, indicating to me that something else is going on in there, to explain why the second motul popint is so much lower and on par with the elf point). Once you are able to subtract out the effects of numerous other phenomena, then you can actually quantify the performance enhancement of Terry's oil. Until we have a grasp of everything else, it could be claimed that breakin or a number of other phenomena are the reason for the wear drop... This is especailly the case because it is not explained how many miles are really truly on the latest double secret oil sample, and what was done beforehand, that might effect results.

In the world of science and engineering, one test is no test, unfortunately.

While a nice little experiment, and a great chance to formulate an oil for these top notch engines, I can't see any validity to the results prior to 10k miles. Unless there is a way to decouple different oil performance from excessive wear due to breakin and hard use, there is too much going on here to effectively draw solid conclusions, IMO.

It will be interesting to see what this super secret oil is, and run it in some more controlled tests!

JMH
 
Thank you for sharing this report. JHZ makes a great point though. You are working with very good people. Looks like your application requires a good ester based oil. What is HOBS? Just curioius.
 
I am only showing part of the data, not all of it. If break-in ended at 7K miles then 2x that would be 14K miles. The latest sample was taken at 18K miles, well outside, using that criteria. However, all samples were quite uniform after about 5K miles, and the data shows a wear curve that is continuous, until the latest oil and samples. I am showing only the 3K samples here, but additional intermediate samples were also taken to show trending. In addition, there are 10 other vehicles with 30 total sample points that have been tested. The trends are quite valid. What I am not showing you are the fuel dilution curves, which are the root cause for the wear.

As stated previously there were 3000 miles on the oil as there were with all other oils. Every oil was changed out after 3000 miles because of severe fuel dilution, which had caused flashpoint to drop to the 220 to 235F range. This is consistent with all other engines measured. Some slightly worse, some slightly better. But the oil had to be taken out for fear of severe deposit formation.

Decreased anomalous wear with Elf is due to an exchange and refresh of the oil with 140 miles on the oil with 3L (30% of the volume, to correct for flashpoint drop due to dilution. Other engines do not show this anomaly.

I will disagree with you, being an engineer myself. One test can be a test if the underlying process is purely deterministic, and you understand it. Whether one agrees with the conclusions is another matter. However, to allay your scientific concerns, of the 10 engines that are under measurement, 3 others have or will be additionally testing this same oil. I would expect the same results. Two have switched to this oil at >13K miles, and one has switched to this oil at 2K miles.
 
Quote:


It has been stated many a time that UOA is not even all that useful until you hit a baseline in your UOA results for which to improve on.




JMH, this assumes that the early UOA does not find a severe problem that trumps break-in wear. We did find this smoking-gun in FSI engine fuel dilution issues.
 
Good discussion fellas. What property(s) of the oil can decrease the fuel dilution in the RS4 engines? My guess would be maintaining the right viscosity which affects ring sealing but I'm not sure.
 
Direct injection doesn't cause fuel dilution. Sloppy OEM programming and running rich does.
A little less blowby from having the rings fully seated would be a cause for less full dilution.

Great data but an engine should be broken in prior to starting a test. Also, after the break in, several back to back runs on the same oil should be done. Jumping around brands, IMO, adds a variable negating some of the data.

HOBs? is that the vegetable oil? high oleic basestocks? renewablelube?
 
RI, how did you break in this engine? Rings should be seated at least by 1,000 miles in a modern engine no? Did you perform any WOT?
 
Buster, Break-in was done aggressively from day one. I allowed the engine to come to full temperature and then performed almost-WOT throttle acceleration and deceleration runs in 2nd and 3rd gear, within the factory rpm guidelines, which still allowed the engine to produce nearly full torque. This was done to force maximum ring pressure in all directions. Once engine oil temperature raised by 15 F, I backed off and cruised on the highway in 4th, 5th, and 6th, until the engine cooled down. I continued to use this procedure during the 1500 mile break-in period.

Subsequently, at 11K miles I placed the car on a Mustang dyno and confirmed that the engine is making full power, using standard Quattro drive line loss correction factors.

Other owners have used entirely different break-in regimes. All who have taken oil samples have shown high fuel dilution , in the 1.5% to 2.5% range.
 
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