"Lifted" from the Mobil web site Material and Safety Data Sheet for 10W-30 weight Mobile Drive Clean oil:
"10. STABILITY AND REACTIVITY
-------------------------------------------------
STABILITY (THERMAL, LIGHT, ETC.): Stable.
CONDITIONS TO AVOID: Extreme heat and high energy sources of ignition.
INCOMPATIBILITY (MATERIALS TO AVOID): Strong oxidizers.
HAZARDOUS DECOMPOSITION PRODUCTS: Product does not decompose at ambient temperatures. [emphasis mine]
HAZARDOUS POLYMERIZATION: Will not occur. [empahsis mine]"
Remember, this data is for finished product, not just the base stocks. Stocking up at a favorable price would leave the purchaser more exposed to having some to use after the next API/ILSAC spec is released than any "spoilage" that might occur with blender-sealed product - particularly since Mobil says the stuff is essentially stable at ambient temperatures indefinitely. I doubt that other brands are any different in that regard. (The raw stuff was in storage at hellish temperatures for several million years...)
[ May 30, 2003, 12:37 PM: Message edited by: Ray H ]