Understanding Cleaning

Yeah, very good advice Carl.

Denatured alchohol works great on any coin to remove gunk/dirt/etc. It now replaces the need for me to use acetone.

Another poor idea. As with any product as I mentioned previously about Olive Oils, manuafacturing processes vary and the end results also vary. Do not use chemicals to clean coins unless you just want a shinny coin of no value. If you ever watch the Antique Roadshow on TV you would have noticed how many times they state "If you had cleaned this, it would now be worthless or close to it". This is extreamely true of coins lately. Back in the old days, cleaning coins was the thing to do. People used to want bright shinny stuff. However, as the coin collecting became so much of a bug business, cleaning coins had become the thing not to do.
You must remember that many of the items you see on a coin as a contaminate has become part of the coin. It usually is a chemical reaction with some other substance. Removing this contaminate will take part of the coin with it.

I too have noticed the differences that different brands and strenghs of olive oil and how it affects the coin. I soak in olive oil just enough to soften any goo in order to remove it. Still sometimes it affects the coin in ways that alters it's tone and which I am not pleased with.
I'm going to use distilled more frequently rather than olive olive in the future.

Also, I agree with Mike's post above.

Another problem with olive oil, besides the variation in ingredients already mentioned, is that it can slowly oxidize, forming lacquer-like substances that may never wash off (other hydrocarbons such as gasoline do this if you leave it in a gas tank for a few months).

As a chemist (and not a coin-cleaning expert), I like acetone a lot better than water, since water facilitates many other reactions (acid etching and oxidation both go faster with water). If you did use water, I would use acetone last (again subject to the high purity warnings already mentioned. I use high-purity stuff at work, which is far more pure than distilled water).

I use acetone to dry things. It washes off the water, evaporates quickly and cleanly, is extremely unreactive, and won't dissolve metals, metal oxides, or metal sulfides (which pretty much describes coin surfaces). Of course, that's not to say when you make a loosely attached particle fall off it won't take some metal with it and be uglier underneath.

Denatured alcohol is different things at different times, often with water, so I don't trust it.

I'd also avoid anything that was stored in a plastic bottle. Not only can the plastic add to the residue problem over time, but most plastics are permeable, so even if the plastic has no additives, that adhesive from the label could eventually soak through. I work with eye-drops, and after years of finding things in the eye-drops that passed through the outer box, through the label, and through the bottle into the solution, I'm surprised they keep the water in. Oh, actually they don't. Many of the bottles lose 5% of the water contents per year, straight through the plastic, concentrating the ingredients by 5% a year.