Found this pretty interesting!
http://members.themotoroilevaluator....dex.php?id=162

Poor Man's Oil Analysis

Oil analysis is really the best way to determine what your oil change frequencies should really be. However, on passenger car vehicles that only have a sump capacity of 4 to 6 quarts, it often can be cost prohibitive, since an entire oil change (even synthetic), wouldn't cost all that much more than a complete oil analysis.
So, for some, the best thing is to perform a "Poor Man's Oil Analysis". It won't give you readings as accurate and precise as results from a lab, but it can give you a fairly good idea of how well your oil is holding up.
1) The Blotter Spot test

This test reveals oxidation products, sludge formation, dispersancy failure, glycol contamination, water contamination, fuel dilution, and high levels of particles.
You want to place a drop or two of used oil on the surface of chromatography paper (good heavy white card stock works pretty well too). Lay the paper or business card flat, but so that all but the very edges of the paper is suspended. For a fairly stiff business card, placing two pencils down on a table and laying the business card so that the ends are resting on the pencils would work well.
You want to wait for the paper or card to absorb the oil drop(s) which might take awhile. Once all of the oil has been drawn into the pores of the paper you can begin evaluating the condition of your oil.
- A colorless spot or slight yellow outer ring - "good" oil.
- A dense, dark deposit zone – Dispersancy failure
- A black, pasty zone – Glycol (Antifreeze) in your oil
- A dark center with distinct outer ring – Severely oxidized oil
- A dark center with surrounding rings – Fuel in oil
Information for the blotter spot test found in:
Fitch, J.C., “The Lubrication Field Test and Inspection Guide”
Noria Corporation 2000
2) The Crackle Test

This test is useful for establishing water ingression into your oil from condensation problems. Typically, you'll be most susceptible to water in your oil if you are a short trip driver and/or if your vehicle sits for long periods without being run.
If you have fuel in your oil, this can cause some disruption of the test, so do the blotter spot test first to see if you have any fuel dilution. If so, that is already a problem, so the crackle test is a moot point.
To perform the crackle test, you place a very small quantity of oil onto a hotplate of some sort which is set to a temperature high enough to boil off any water in the oil. Since most oil isn't volatile until it gets up around 375 degrees F or higher (synthetics much higher than that), you could set the plate to a temp anywhere between 250 and 350 degrees most likely.
At that temp, when you place the oil on the plate, you'll hear a crackle as the water boils off. Should occur very quickly as long as the amount of oil you use is small.
If there is no crackling, then you know there is no water present. An oil analysis is more precise in that it will tell you if the level of water in the oil is a problem and what that level is, but the crackle test is a good cheap way to establish water ingression.
3) Used Filter Inspection

This is pretty simple. Cut your filter apart and see what's in there. If you see large amounts of metal shavings, some of which seem fairly large, you may have some serious wear issues.
Also, if you have sludge problems, often you'll see the remnants of it within the filter media as little "blobs" of "gummy" oil.
4) Oil on Water

Simple test. New oil will bead up when dropped onto the surface of the water. Just a drop and you'll see. Either there is a little drop of oil that maintains its integrity or the oil drop spreads over the surface.
If the oil drop spreads, the oil is likely overly contaminated and/or oxidized.
5) The "Rub" Test

Shortly after a drive (but long enough after that your oil isn't so hot it will burn you), take a drop of oil from your dipstick and rub it between your fingers. If the oil feels particularly "grainy", it is pretty contaminated and should be changed.
6) The "Smell" Test

Smell the oil. First, get out a bottle of new oil of the brand and type you used for your last oil change. Smell it so you know what it should smell like in good condition.
Then, take a few drops of oil from your dipstick and put it on your finger or on/in some other medium. Smell it. If it smells "burnt" in comparison to the new oil, you may be in need of a change, oxidation has occured.
Now, understand, some oxidation is natural, and the presence of oxidation itself is not necessarily an indicator that an immediate change is necessary. It just means that your oil is not in as good of condition as it was when it came out of the bottle.
The same is true of many of the tests above. Only oil analysis can truly give a quantification of the problems listed above so that you can truly know how "bad" your oil actually is. But, the "tests" above are a pretty good way to get a decent idea of whether your oil is ok for continued use or whether you should at least CONSIDER changing it out.