I haven't seen any detrimental effects. From what I've read, admittedly little, I don't see any reason to worry in regards to o-rings.
Buna-N (Nitrile) is suitable for dynamic and static seal of o-rings in the environment containing the following chemicals: Acetamide, Acetic Anhydride, Acetylene Gas, Air below 200 C, Aluminium Chloride, Aluminium Flouride, Aluminium Nitrate, Aluminium Sulfate, Cold Gas Ammonia, Ammonium Nitrate, Ammonium Persulfate Solution, Ammonium Sulfate, Animal Oil, Argon, ASTM Fuel A, ASTM Oil One, ASTM Oil Three, ASTM Oil Two, Automatic Transmission Fluid, Beer, Benzine (Ligroin), Boric Acid, Bunker Oil, Butane, Butter, Butyl Alcohol, Calcium Carbonate, Calcium Chloride, Calcium Hydroxide, Calcium Nitrate, Calcium Sulfide, Carbon Monoxide, Castor Oil, Tung Oil China Wood Oil, Citric Acid, Cod Liver Oil, Coffee, Coolanol Monsanto, Corn Oil, Cyclohexane, Denatured Alcohol, Diesel Oil, Diethylamine Glycol, Dow Corning 550, Dow Guard, Elco 28 Lubricant, Ethane, Ethanol, Ethyl Alcohol, Ethyl Chloride, Ethyl Hexanol, Ethyl Silicate, Ethylene, Ethylene Glycol, Formaldehyde, Freon 113, Freon 114, Freon 12, Freon 13, Freon 32, Freon C318, Freon TF, Fuel Oil, Automotive Gasoline, Gelatine, Glucose, Glycerin, General Glycol, Petroleum Base Grease, Helium, Heptane, Hexane, Petroleum Base Hydraulic Oil, Hydrogen Gas, Iso Octane, Isopropanol, JP 3 MIL-J5624, JP 4 MIL-J5624, JP 5 MIL-J5624, JP 6 MIL-J5624, Kerosene, Animal Fat Lard, Linsed Oil, Liquefied Petroleum Gas (LPG), Petroleum Base Lubricating Oils, Mercuric Chloride, Mercury, Methane, Methyl Alcohol, Methyl Ether, MIL-F-25558 (RJ-1), MIL-F-25656, MIL-H-5606, MIL-H-7083, JP-5 JP-4 JP-3 MIL-J 5624, Milk, MIL-R-25576 (RP-1), Type 1 Fuel MIL-S-3136, MIL-S-81087, Mineral Oils, Naphtha, Natural Gas, Neatsfoot Oil, Gas Nitrogen, N-Pentane, Oleic Acid, Peanut Oil, Petroleum Oil, Potassium Nitrate, Potassium Sulfate, Producer Gas, Propane, Propanol, Propyl Alcohol, Transformer Oil Pyranol, Red Oil, RJ-1 (MIL-F-25558), RP-1 (MIL-R-25576), Sea Water, Silicone Grease, Silicone Oils, Sodium Bicarbonate, Sodium Carbonate, Sodium Chloride, Sodium Hydroxide, Soyabean Oil, Stearic Acid, Stoddard Solvent, Sucrose Solutions, Tannic Acid, Tartaric Acid, Type A Transmission Fluid, Turpentine, Fresh Water, Whiskey.
Common O-Ring materials that are SUITABLE for dynamic and static seal in the environment containing Automatic Transmission Fluid include:
Buna-N (Nitrile): Buna-N, also known as Nitrile rubber, is a synthetic rubber copolymer of acrylonitrile (ACN) and butadiene.
ASSUMPTION: By Millable Polyurethane, they mean common urethane o-rings. This ranking of material is supported by the chart below this webpage. However, I very likely could be wrong. Please feel free to correct.
The O-Ring materials below are USUALLY SUITABLE for static seal in the environment containing Automatic Transmission Fluid.
Millable Polyurethane: Millable Polyurethane rubber is made from both polyester and polyether polyols.
In regards to automatic transmission fluid, they rank Nitriles as "compatible" and urethanes as "minor incompatibility." That's the same as what they rank lubricating oils, petroleum-based. Transmission Fluid Type A is ranked "compatible" for both. Same as mineral oil which I've used in a pinch. http://cmrubber.thom...ility-Chart.pdf
I don't know the exact composition of "paintball oils" so researching their properties usually leads to a bunch of marketing claims. I'm open to reading up on actual data if there are links I'm unaware of.
However, I also need to admit that I have no actual data to show. So I propose this. I will test o-rings in ATF, mineral oil, synthetic air tool oil, and Gold Cup Gun Oil.
It seems to be about the cheapest of the paintball oils so I could stomach buying a few oz. of it. I'll use these o-rings as they would be common ones paintballers use:BunaUrethane
Tests I can think of:
1. Thickness of O-ring (ie. digital calipers)
2. Load weight before shear (ie. hang one from a nail and load it up with fishing weights until it snaps)
3. Compression test (ie. how many twists in a clamp for a simple elastic/plastic test)
4. Tests above a different temperatures (ie. colder)
5. Test above over time (ie. a month or more between tests)
Any other tests anyone can think of? What sample size would you guys be happy with?