i had been running it. but murphy oil started going around collecting all the used cooking oil from the fast food joints and cut off my supply of used oil.
Same thing here, with big stickers on the tanks telling how it belongs to the waste company and they'll prosecute you for theft.
I've run up to 20% vegetable oil mixed with regular gasoline in my 1980 Malibu. Smelled a bit odd at idle, but started and ran fine, mileage went up about 1.5mpg, probably because the factory smog calibration in the carburetor is very lean, so it was closer to stoichiometric with the SVO.
I'd still be using it if it was still available for free.
I used to run about the same proportion of Diesel to gasoline, back when Diesel was cheaper than gas. Been a long time now.
Diesel mixes fine with gasoline, but you have to premix vegetable oil, which is a pain in the ass. Once it's stirred and mixed, it stays that way - I let test burets sit for a week in the freezer, and a month out in the shop, with no separation. But if you just pour it into the tank it'll run to the bottom and get sucked up by the pickup tube, the carburetor will fill with straight oil, and you'll find that gasoline engines *really really* don't like that. Fortunately the engine was fully warmed up and I was on a long straight road after dumping some oil in after refuelling. I moved along wide open at about 25mph for twenty miles or so before it cleared, limped back home, and had to put new plugs in. On old G-bodies like that you have to either have prehensile hands or you jack the car up, take off the front wheels, and access the plugs through the fenderwells. <sigh>
I also tried 25% nitromethane/alcohol (model air plane fuel) injection through a spraybar in the air cleaner lid. The nitro dissolved the plastic on a couple of windshield-washer pumps I tried. I thought the nitromethane would work like a poor man's nitrous oxide setup, but the car actually lost power when I hit the switch. I figure the 75% alcohol part cost me more power than I gained from the nitro, and I was probably airflow-limited by the ~200CFM Rochester DualJet carburetor anyway.
"Diesel-Kleene" or other Diesel fuel additives work great in gasoline engines. To simplify things considerably (for detail, get Glassman's "Combustion, Third Edition" from the library) the additives make fuel easier to light. In Diesels, it increases the cetane number. In gasoline engines, it makes the fuel easier to light and faster to burn, without making it more sensitive to detonation. Running is noticeably smoother and gas mileage goes up. However, after checking mileage through several tanks, I came to the reluctant conclusion that, price-wise, it was a wash. Plus the additive stinks to high Heaven, and even the empty funnel will stink up a station wagon.
Uh... I've played with fuels a bit.