I will share my past with BD oils and you decide if it works for you. I have a link (see below) that you can gather some insite about oils and what may work for your personal BD use. I have used different oils for over 25 years and some are better than the rest. Taco Bell has always had a high field titration of 4 to 7 grams per liter. The reason is all the different products have deep fry batters that have flower and STUFF (magic sause) before going for the oil bath. I tried long John Silver Fish and Chips, and KFC, Again to nasty for my personal use. McD and BK suck too. Carl Jr, Jacks BOX, and the like have contracts and or they are starting to make their own BD now. You have a better chance with private small business owners. Check with local building permits and health dept for new business start up. Get there first.
Now that Greek joint could be real good, but for me to know for sure, you need to send me some samples of their food, just one of everything would be OK, then titrate test the oil before you haul it home. Nothing worse that a bunch of nasty oil that cost you $1.50 a gallon to make and all kinds of goo from pre filtering and then it clouds up at 40'F and jells at 38'F. This link is hard reading for some. But give it a try, read it all and keep going back to it over time and it WILL begin to fall into place as you start to gather oils.
http://media.wiley.com/product_data/...0471385522.pdf
Pass it around to others for them to read. It was something I was given a few years ago, from my BD mentor.
All oil will make biodiesel, some are better than others. The best test for oil is field titration, then ask yourself what type of oil, the temp that it was for cooking and how long between changes, what it cooks, how much trash is in the oil ie: flower, meat, etc. because all of that crap holds tiny traces of moisture and water is NOT our friend when making BD.
IMPORTANT: TEST all OILS BEFORE YOU HAUL IT HOME, sneak in and get a gallon of it, bring it home, heat it up a little and titrate test if for free fatty acids. If it is low titration, say 1 - 3, go in and eat and leave a bigger than normal tip. Next visit ask if you can pick up some oil because you are playing around with making BD at hope. Them bring a tiny sample of BD in an oil lamp for the owner or manager. Be proud of what you made with their oil, and leave another nice tip. Then ask if it is OK to place a drum behind the joint to collect your own oil.
Enjoy !!!