thoughts on cooking oil for engine oil?

I'm doing some experiments on using cooking oil as engine oil, partly for green living brainstorming and "backup plan" experiments. I'm using a number of well worn (read "donated and thrift store finds") lawn mowers, and while I have found relatively few issues, though I still wouldn't use it in my truck unless I was in a world of hurt. They seem to overwinter fine with the veggie fat in it, which supprised me a little, but still had a bad engine turn rancid after 2 years, much longer than expected. I would really like to track down an oil testing kit, haven't seen any in awhile. Anyone else have any thoughts?

Some things I have found is that Tecumseh engines don't like fat oils if ran for an hour or so, but Briggs & Stratton motors don't seem to care. However, both my Tecumseh motors are troublesome anyway, and all motors tested burn oil anyway. One motor literally sprays oil from the crankcase vent, which does not lead back to the carbeurator for some reason.

A few years back I had an Artic Cat 500 atv and well I found myself in the mountains in Utah 90-100 degrease 25 miles from no where and the oil plug had worked loose yes I lost it and the oil,,,,,,,,,,,,,,,,, We had ben camping and had a half gallon of peanut oil with us, me and my 16 year old grand son weren't walking out, I made a plug out of wood and filled it up with peanut oil ,,,,,,,,We made it out I was really supersized had the Dealer take a look at it when we got back He was surprised too ( no problems found ) just letting you know the power of peanut oil try it an get back to me id like to know

Like I was saying earlier, the B&S engines I use corn oil in and they run fine the Tecumseh engines seems to overheat with corn oil.

Also, I got the idea of this because I found that they used to use fat oils in car motors back in Woorld War 1 and maybe World War 2. It's plausible I may can use it in my truck but I don't want to do so unless I have to.

do some testing with peanut oil I here it has a higher smoking point you may really be on to something

Peanut oil does have the highest smoke point of any oil I have found, but even bacon fat is listed with a higher smoke point than motor oil. However, fat oils do oxidize and caramelize on parts sometimes in the wrong conditions. A lot of good info is also on www.rcgroups.com regarding a somewhat similar castor oil.

Cooking oils have poor lubrication properties compared with real engine oil. However, for technical reasosn, some engines tolerate poor oil much better than others.

Small engines, like B&S lawnmowers are designed for use with splash lubrication systems, (no oil pump). They have loose clearances and low stressed parts so they can use poor oil with little short term harm. I remember my dad accidentally mowed his lawn (15 min) with a B&S engine with no oil in it at all - and no harm done.
However, I would guess such an engine would not last as long with veggie oils in it, over the years.

Most motorcycle and ATV engines use roller bearings for the highly stressed parts. Again, such engines tolerate poor oils fairly well.

By comparison, almost all cars and trucks use plain bearings which need a hydrodynamic film of pressurized oil in the bearings to function. Cooking oils shear more easily than real engine oils. If the engine is loaded beyond the shear rate the bearings will be wrecked in short order. So.... don't put veggie oil in your car :)