I am surprised, given that we are now in* The Future*, that no-one has been able to design an engine that does not use oil. What are the obstacles?
I mean for lubrication…
The obstacles:
Engines have moving parts.
Moving parts create friction.
Friction results in heat.
Heat destroys engine components.
Unless we can come up with some material that significantly reduces friction and is usable at high temps we’re stuck with oil to lubricate.
Forgot to add, if we do find some material that fits the bill it has to be cost effective or we’ll just keep using oil.
I am talking about the massive amounts of oil that an engine contains (several liters). Why can’t an engine be designed to use only a tiny amount? Is the oil a heat-sink in addition to a lubricant?
what if we made the engine OUT OF oil?
:eek:
i’m blowing my own mind
What would you lubricate THAT with? 
Would an oil change become much more expensive, since it’s a full engine change?
Yes, the oil acts as a transfer medium to move heat away from hot areas. Many engines have oil coolers to facilitate the cooling effect. The oil also removes wear particulates and carries them to the oil filter.
There are oil less air compressors using Teflon ringed pistons in place of oil lubrication. They wear out fast compared to a oil lubed compressor.
Oil definitely gets hot and the less you have the hotter it’s gonna get. Small amounts burn away as well and it gets fouled in the process. Less oil means it gets fouled quicker. Think of it like this, if you put a drop of vinegar in an ounce of water you’ll probably be able to taste it. If you put a drop of water in a gallon the fouling is greatly reduced. Heat is the same, a drop of boiling water does much less to a gallon that to an ounce.
I suppose it would be possible to build an engine that used a lot less oil but you’d end up changing it much more often so it really doesn’t give any advantage.
with the price of oil it’s a hot topic.
The old VW engines used just short of 3 qts of oil. And it really needed to be changed every 3000 miles and it was really black when it was changed.
It is possible to make an engine with magnetic bearings. But you would loose cooling effect of the oil.
Got it. In relative terms, how important is the cooling as opposed to the lubrication?
A better idea is to design an engine that doesn’t require coolant. A significant amount of power is used to circulate coolant through the engine and radiator.
Well, air-cooled engines have all but disappeared in autos. I think the last one was a Porsche in about 1999:
http://en.wikipedia.org/wiki/Porsche_993
Of course, engines with fluid coolants can be made more compact, I should think.
I loved those.
Newer VW/Audi engines hold large quantities of oil.
Your car already has an engine that is perfectly capable of running without oil—if by “without oil” you mean using synthetic oil in place of the traditional stuff.
Depends on what you consider an “engine”. There are diesel fueled turbinesused as range extenders in hybrid vehicles that have one moving part and no oil.
Don’t be silly. Synthetic oil is still oil and is petroleum based.