A long standing good friend used the reclaimed cooking oil in his diesel car. It ran OK, but needed constant renewal of the bits of rubber tubing. He knew it needed renewing when he saw the veggysel dripping out underneath it. Probably cost more in lost oil, replacement rubber, and extra hand washing and aggravation than it was really worth. I gathered that was his opinion when he went back to using "proper" fuel.
I'm currently running a Citroen. It does demand the expensive stuff for its diet. Using Asda fuel caused a pollution prevention system warning light to come on after a couple of tankfuls. But that's a more modern car with lots of the modern electronic gubbins.
Long ago, the firm decided to stop using huge standby batteries and go for smaller ones with a diesel standby generator and automatic control box with a big enough tank to last a fortnight or so. Many buildings were also oil* heated. Being the spare hand on the staff, I spent a lot of time covering for other people. So it was that I went to one building, and about 11 or so a tanker rolled up with the intention of dropping off about 1200 gallons. He had, by habit, parked near the boiler room, I let him at it, signed his chitty, and away he went. Next morning my boss rang.
"Have you run it?" HE said, eagerly
"Run what?" Said I, puzzeledly
"Your new genny" said HE, worriedly.
So next morning the tanker came again, and the juice got put in the right tank. Both boiler and standby generator worked fine, it was the same stuff. For all I know, most of that original oil is still down there. It certainly never got more that routine test use since the early '70's.
*35 sec it I remember right.
