It's difficult to legally find quality WVO on the road. Even if you do find a stash out at 12am behind Joe's Grill, you will likely struggle pumping it though filters and be worried about what exactly you are putting in your vehicle.
I have a bunch of 5 gallon carboys I carry with me for shorter trips with my car. Sometimes people tow 275gallon totes or barrels on a trailer or in their truck bed.
For longer trips, I prefer to connect with other Veggie-heads who have some extra oil to sell. How do you connect with those people? See the following links:
Fillup4Free - An older, but still fruitful map of people with oil to sell
Forums - Post a request for oil in a specific location or find others selling
http://www.wvodesigns.com/forum/forumdisplay.php?22-Open-Market
http://biodiesel.infopop.cc/eve/forums/a/frm/f/559605551
Craigslist - Search for "clean WVO" "veggie Oil" "vegetable oil" etc
If you really want to dumpster dive on the road, and your family or friends don't mind hunting around a bit and finding some good oil, then by all means go for it. Cleaning it is always the challenge. The best thing I've seen for on the road filtration is the Golden Fuel Systems One Shot Filtration unit. I haven't used it, but it has a nice large filter for cleaning oil that hasn't been settled or screened.
See the One Shot Filtration Video
-Jason Jelonek
