I tried to compare the cost of SVO and diesel. A gallon of SVO at the local supermarket costs $8.79 and diesel costs $2.55. That didn't look so good. I didn't think it was a fair comparison because SVO comes in a nice bottle and it's edible. If it came out of a fuel pump for use as a fuel it would be much cheaper. It wouldn't have to be packaged or edible.
Still the question remained, how to compare the cost.
I decided to look at the futures for soybean oil. Soybean oil sells for 24.93 CENTS per pound. It's specific gravity is .92. In other words it weighs .92 kilograms per litre.

1 liter = 0.2641721 gallon [US, liquid]
0.92 / 0.2641721 = 3.4825 kilograms/gallon
1 kilogram = 2.2046226 pound
3.4825 * 2.2046226 = 7.678 pounds/gallon
So 1 gallon of soybean oil costs $1.91 (7.678 x .2493).
And a gallon of diesel costs $2.55 at the pump.

It's not a fair comparison because soybean oil would cost more at the pump. And, if they taxed it like fossil fuels it would cost much more.
But, to be fair to soybean oil it sounds like it needs much less refining than crude oil. Heck, you can do it yourself.
It's not a fair comparison but it's better than the cost of a gallon vegetable oil at the supermarket versus a gallon of diesel at the pump.

There's still the question of how much energy it takes to grow soybeans. How many barrels or fractions of barrels of oil are used to produce a barrel of soybean oil? It's got to be positive or it's not worth the effort. You might just as well burn oil directly. Oil drilling is not good for the enviornment but farming isn't exactly good for it either.

well, would you rather the oil from the fryers(where they are getting it from) go to waste? they are using used oil in their vans. i talked to a friend of theirs though and they have a contract with mcdonalds to use their oil, and unfortunatly, they have gone through like 3 or 4 vans because theirs keep breaking down. i think its because they made their own system, and it isn't a solid design.

It really is a good idea to use that used oil as motor fuel. But do really think that there's enough French fry oil to make a significant impact? If biodiesel becomes widespread the vast majority of it will be SVO.

Who has a contract with McDonald's? The Grease Not Gas guys? That's totally not true. Not one of their vans/rv's has ever broken down from a WVO related problem (It's usually just because they're old used vans and a wheel falls off or something). Besides, anyone who has done anything with waste vegetable oil conversion knows that restaurants such as McDonald's do not provide adequate grease. It's far too disgusting and the custom filters would clog in no time.

Here's a hint to anyone interested - Get your grease from the cleaner asian restaurants that are out there. You can get about 10 thousand miles on that stuff before even thinking about the filter. Don't even consider fast food restaurants even if you're desperate.

I've been using WVO since 92 (when everyone thought I was a little weird), and at the time could get more of the stuff than you could cart away with a semi tanker. I now have two mercedes 300 SDL cars, a diesel lawn tractor, a VW Rabbit diesel pickup, and a mercedes powered pontoon boat. And guess what, the restaurants around here are now beginning to charge for the stuff, (present rate is $.25 gal and rising) and if that's not bad enough the barrels I furnished to several of the restaurants now get pilfered on a regular basis by a group of ol ex hippies who have nothing better to do than filter the stuff and sell it to a growing number of local users! That is a trend that's definitely going to continue, and in fact some distributors of cooking oil are now beginning to "lease" the oil and then reclaim it themselves and process it into biodiesel. So enjoy the free ride while you can, it's going to change!