Quote Originally Posted by volvoscrapper View Post
hmmm. if you lived in constant 70 degree weather and drove your car a few miles then shut if off, maybe.

problem with vegetable oil is, temperature-wise it performs the opposite of motor oil.

A blended motor oil with "pour point additives" will have low coalescing at low winter temperatures, say 10, and more coalescing at high temperatures, say 40. So you have 10W-40 oil. The oil has to be thin when cold, then more coalesced (higher viscosity) when hot to protect against shear.

corn oil, on the other hand, has a viscosity of 50 at 75 degrees F, but drops down to 5 at 212 degrees F. Worse than that, when you get winter temperatures, the viscosity may be something like 110. So you have oil that is essentially 110W-5. That means it is too thick to crank when cold, too thin to protect when hot.



In an emergency, yeah, I'd add some. But I wouldn't plan on driving far or heating things up, and then I'd drain it.
Yes, get it out asap.
Take a 10w-40 oil. When it is cold it flows like a cold 10 weight [a cold straight 40 weight would not flow good]. When 10w 40 is hot it flows like a hot 40 weight where a straight 10 weight would be too thin. As a general rule if your engine calls for 10w-40 it is ok [passably better] to use 5w-40 or 0w-40 but it is not a good idea to use a 10w-50 [I don't know if they make a 10w-50, just an example]