That's fasinating. Once again, it illustrates that what's good for the track isn't necessarily what's good for the street. Wanna-be racers—like myself, need to pay attention to these things. Thanks again, Richard. You're the man!

I've ordered a 190°F thermostat and hope that's the end of my issue. 

K&N filters let a little more air at very high rpm's. That is their only advantage. But, where a paper filter removes 96-99% of the dirt, while the K&N removes 85% if well oiled on controlled ASTM test procedures. Unfortunately, there is a very poor air filter selection for Minis, until you get to the SPI (maybe more, but I haven't seen all the years). The stock SPI system is unbeatable. 

Richard, many thanks for your very experienced comments about oil over the years. I hate to nitpick , but:
i do not understand the comment "higher for K&N".
Everyone seems to think K&N is the best air filter, so should that read "lower for K&N"? Harvey

Kimball has a lot of good points. pretty much right on.
I have analyzed over 5000 oils in the last 20 years. For the average driver, it does not tell you much unless you do it consistently, and the data from the lab does not mean much, as it compares your oil to averages. Blackstone adds valuable comments, but again, they compare to averages, not to Minis. (Since some of the oils in the market use a Sodium sulfonate detergent package, the average for sodium is not representative of most oils).

Oil analysis is very helpful to big companies. When someone has 40 identical pickups, you can set baselines, benchmarks, and really evaluate maintenance and driving habits. But don't bother analyzing any oils before driving 5000 to 10,000 miles. The silicon in the seals and gaskets will show up the same as dirt, and the first few changes will have the particles of break-in.

Obviously, look at viscosity and fuel dilution. Low temp operation and short trips are 90% of the problems in most, but fuel injected cars can have poor seals. But fuel can also be detected by smelling, or putting your dip stick over a candle. If the vapor flares up, you have fuel in the oil (but not enough to be dangerous. It is a field trick we use all the time. 

In a manual transmission mini, a cheap oil viscosity may have sheared in the transmission, as the gears grind the polymers. So if the viscosity is no longer in range, and no fuel, find a better oil.

Look at the silicon. That is dirt, and will tell you how your air filter is doing. High silicon will cause high iron wear. The two graph lines will be close to parallel. You should not have more than 5-8 ppm of silicon if your filter is good. (higher for K&N)

Look at water, glycol, and sodium. Hopefully everyone uses antifreeze, so glycol is the best indicator of a head gasket, but water, or evaporated water resulting in sodium residuals should be investigated.

Look at the TBN (TN, today). In a gasoline engine, 3 is ok.

You can look at the zinc and phosphorous levels to see that they are reasonable. but their depletion doesn't really show up in an oil analysis, as the elements may still be there, but incapacitated (no longer effective).

And finally, if anyone does get an analysis, PM me with a copy and I'll be happy to comment.

As I mentioned, my carb settings are fine according to my mass O2 meter and plug color. I never take short trips and have a pretty light foot on the throttle. One thing though, my water temp gauge rarely gets over 175° F, and if, as you say, the Mini tends to put fuel into the oil anyway, 175° probably isn't hot enough to volatilize the fuel. My second oil analysis showed considerable fuel in the oil, but not in the danger zone according to the lab. I've considered blocking off my oil/water heat exchanger see if that brings the temp up a bit, but installing a 190° t-stat might be the best way to go. Thanks for the tip!

As Spank says, it's not a one-time thing. I tested regularly in order to set change intervals, as my chosen oil is $44/gallon. Gas in oil is common in our beasties, and yes, it IS mixture issue... SU's "throttle pump" is the thickness of oil in the dashpot, cold weather and lots of cold starts will fuel up the oil. So will short trips, so will changes to gas brand so will... anyhow, it's endemic to carburetted engines in  the modern fuel chemistry of today. FWIW changing your thermostat to a 190 will fix this... if you don't run one, expect fuel in your oil.

Note that Blackstone has only limited experience with minis 'cause too many of us are cheap b**tards. Things to looks for are diminished zinc levels - this means your oil supplier is cheating as it doesn't go away in usage Copper or brass in any form is BAD - bushings and thrust washers are the only items made of this, or worse, the second layer of main or rod bearings if you're using the good stuff. The things to look at are general viscocity breakbown and acidification. These will tell you when to change your oil. On that part I've found that the race car cruds up its oil with nasty particulates LONG before the oil gives up.
For the street car? Totally worth it, but expect to do four or five sample runs for anything meaningful. What I got out of it was what oil to use (of three I had been using), what oil change intervals (I'm at 4500), what t-stat worked better (190) and what vis brought the least particulate (15W50 Motul in the race car, 5W40 (Shell T6 is the latest) in the street car - this is combining and after analyzing both race and street car testing. About a dozen samples, probably more...

Now for your street car? Mine has 39k on it since the last engine out. How much do you actually drive? That's the real issue.

That's a good question. Other than monitoring zinc levels, what action would take? I've had an analysis done twice on 'Rosebud'. The first time they reported I had a significant amount of gasoline in my oil. They said that high levels of gas can be caused by 1) an overly rich mixture 2) a heavy right foot 3) short trips that don't allow the engine to reach operating temperature. I didn't think any of these applied to 'Rosebud'.

However, I noticed that when I turn the electric fuel pump off and shut the motor down, my fuel pressure gauge shows 2.5 psi remaining in the fuel line for 30 minutes or so. I thought perhaps that fuel was getting past the float valves, trickling down the cylinders and into the oil. I tested the seal on the valves, and they're fine. So, I began turning the fuel pump off about 30 seconds before I turn the engine off. That brings the fuel pressure down to zero.

It's a bit of a hassle and I only remember to do it about 80% of the time, but it solved the problem. The next analysis showed an acceptable amount of gas in the oil. The analysis is about $25 dollars a pop, but I got my money's worth.

That makes sense that you would continue to use it for a long time. I was just curious about it with all the talk about the flat tappet cams wearing out due to the new oils not having enough Zinc. It would show up in the analysis I would think. I've been using the Rotella that is said to have enough zinc, so I'm hoping I'm ok anyway.

Just curious, what action would you take if you see wear? 

A magnet drain plug, and a paint filter will give you some idea from oil change to oil change.

It's not a 1-time thing. You need to do consistent analysis at regular intervals and look for changes in the profile. You'll get a basic interpretation, but you yourself will need to figure out what readings or parts of the analysis you can ignore because of the gearbox stuff.

Valuable information for the racer with the high dollar engine. For someone and their daily driver mini? not so much.

I was wondering if doing oil analysis is worth it on a mini since the transmission and engine share the same oil? I figure there would be wear in the trans that would show up in the test and you couldn't tell if there is actually abnormal engine wear.