Boy, this thread initially ****** me off, then depressed me. Needless to say, I'm happy to that you've apparently got this under control - at least to the point where you're poolside w/ a beer in hand. I remember reading a thread on The Pool and Spa Forum a year or two ago about someone having paint (oil-based, if I recall) dumped in their pool. What a gutless, mean-spirited thing to do.
When we built our pool in August 2007, we also built an overhang on the patio adjacent to the pool decks - but while it's wired for a floodlight I've never gotten around to actually installing one. My wife just had the kitchen remodeled and the electrician isn't quite done. When he returns next week I'm going to have him install a twin flood on the overhang, as well as replace the flood on the back of the house above the overhang (the overhang blocks one side but I can buy a single flood and point it toward the masonry wall on the far side of the pool and the equipment deck beyond - I'll point the motion sensor toward the top of the wall to detect anyone/thing walking along the top of the wall/along the fence on that end of the pool). Also going to replace the twin flood on the outside wall of the sunroom that sits above the walkout on the other side. Going to set motion sensors on all 3 to highest sensitivity and leave them on! I wonder if some security website out there sells a flash unit that could be slave to the motion detector. Even if there's no camera attached, it would add some deterrence value since trespassers would think there was a camera up there somewhere. I'll probably install small locks on the door of my EasyTouch control panel, too. An inconvenience, but will keep anyone from messing w/ things.
OK, rant over, I do have some advice to offer, in no particular order:
1) I use skimmer socks year-round, and half the time I use BioGuard Skim-Mor socks. They are treated w/ mycelx, which was developed for oil-spill cleanups but is also widely used in commercial applications to filter oil from water. It has revolutionized those industries. The socks won't keep sunblock and oils from adhering to your waterline before they reach your skimmer(s), but I truly believe they keep that stuff out of your filter. Try a 5-pack (around $12) or two and maybe that will accelerate the last stage of your recovery. They're blue in color, you know they're working when they turn a greenish color.
2) I found an MSDS for DOT 3 brake fluid:
http://www.championbrands.com/MSDS/1400.pdf
It's definitely glycol-based, and is evidently 100% soluble. Also appears to become flammable when you introduce chlorine, although I highly, highly doubt that's the case with the dilute concentrations of glycol and chlorine in your pool. FYI, mycelx won't absorb glycols.
3) I'd suggest closing your pool a bit later than usual this year, and doing a few partial drains and refills before finally closing.
4) Finally, if you do some google searches, I bet you can find some mycelx mats or pads which you can use to wipe down your liner, skimmer boxes, and the internal components of your filter (****, call Mycelx directly at 888-306-6843 or 770-534-3118). Mycelx absorbs all sorts of hydrocarbons but will not absorb water - meaning it will absorb/remove oil along the waterline (and even underwater, although that should be a non-issue since oil - at least motor oil - floats on water).
In sum, being an owner of a vinyl-lined pool (as am I), you probably know that you can't completely drain your pool w/o serious risk of a shrunken liner that will need to be replaced (the risk increases greatly as the liner ages). But you can safely drain to a level of about 18" or so in the shallow end (someone please correct me if I'm off on safe drain level for vinyl pools). That's alot of water to drain and refill even once, much less repeatedly, but you do it every year at closing. I'd recommend doing it 2-3 times before closing - as well as wiping down the entire liner at waterline and above, the skimmer box(s), return jets, any ladder(s), the step section and the inside of your filter + all internal filter components with some sort of mycelx material after every drain cycle. Probably overkill, but the combination of draining/refilling and wiping would probably reduce any glycol and oil residuals to nominal levels, so you can put this sad episode behind you and forget about it next season and the season beyond.
Good luck!
EDIT: didn't catch your reference to pig mats. I'm not sure, but NewPig products may well utilize mycelx or a similar technology - I see they offer a product which absorbs oil but not water. You're well ahead of the curve. Would still recommend the drain/refill/wipe cycle (using mycelx or NewPig oil-only wipes).
I can't believe people can be so hateful...that's the second motor oil incident I've read about just in the last few weeks!
