Extracting energy from our used motor oil
 

I've been a DIYer, saver, and economizer (miser?) for years.

I generally save my used motor oil in WWF jugs and drop it off at the auto parts store on the next trip.

A while ago I read the "Mother Earth" plans for making a space heater out of an old electric water heater some frying pans, and some asbestos (!). At first I thought I would do that but I don't really have a place for it, nor a good source for used water heaters.

Lately, with my focus on MPG, I have been researching water injection, mostly so I can run 87 in my Camry which calls for 89 without activating the knock sensor. Of course around here there are only 87, 91, and 93 and I hate to pay more for what I don't need, and I am not going to try to do two separate transactions to get just what I need.

Anyway I was thinking about how some add methanol to the injection mix. I also see where some people use the PCV system as the intake for the water. The PCV system is designed to burn off the crankcase air, which, wouldn't you know, consists of a fine mist of engine oil droplets, among other things.

Cue some more research, and it turns out economical (and slightly eccentric) diesel owners have been dumping used oil in their tanks for years. Some go so far as to use a 50-50 mix with few if any ill effects. Some use whatever they can get--after an OC it's motor oil, other times it's whatever they can get from the local Chinese joint.

Now gasoline and diesel are different creatures, but a gas engine is obviously built to tolerate the ingestion of some used motor oil.

Many people advocate the use of a catch can in the low pressure side of the PCV system to catch the droplets to prevent intake/valve fouling. Fair enough, I do that on one of my cars myself.

But this used motor oil clearly contains BTUs that are probably going to be burned off at some plant anyway. Any ideas for extracting that heat within a gasoline engine? Anyone tried it, maybe 1:10 or something in their gas?

I also wonder if it's not possible with a regular gas engine, perhaps addition of a WWF injection system could help it work? Maybe there's even a way to make an emulsion for single source injecting?

I know I probably sound like the guy who wants to convert his lawnmower to diesel, but you can't fault a guy for asking, right?

I had an old Fiat 128 that ran out of gas late at night about 100 miles west of Ottawa. All I could beg was a gallon of snowmobile gas-oil mix. It ran fine and gave me 25 miles to find an open gas station.

My guess is that as long as you filter out the sludge, you could mix it with gas just fine.

Used engine oil has more Btu's than diesel. I've been recycling my UEO for a few years into my diesel tank. Can't say that I've tried it in gasoline.

I wouldn't risk this in my car, but maybe the lawn mower; it ran on 95% alcohol before with no problem.

Not sure you would want water injection, my understanding is that this was used in highly boosted (think turbo- or super-charged piston engines) to cool the intake charge. Used for making lots of power.

Alcohol injection, OTOH ... I understand that GM or Ford has been experimenting with something called "Ethanol Boost Engine" or similar. Idea being a super-high compression engine, running with gasoline. At peak loads, ethanol is injected to raise the octane and prevent predetonation.

One problem that comes to mind is puddling. Evidently fuel tends to puddle in the intake system (even with fuel injection) and I would imagine water would behave similarly, and I would worry about hydolocking the pistons and killing the engine.

Out of curiousity, what does your research indicate?

Used motor oil? I would assume that stuff would be filtered to remove particulates, etc.?

I was thinking of attaching Peltier devices to the exhaust system to generate electrical power...

Doesn't burning oil in a gasoline engine cause problems with the catlytic converter?

It's water injection effectively raises the octane rating of gas. The alcohol has more of a cooling effect on the intake charge, making it more dense. I pretty much came to the conclusion last night that traditional WWF is fine for injecting. Just need to find an appropriate delivery system. Some kind of venturi before the throttle plate seems the best bet. Not too worried about puddling, I can use a WAI and/or route the tubing near a heat source to make sure it's nice and warm. WWF fluid injection, done properly, can definitely be a big MPG booster.

Yes, burning oil in a gasoline engine affects the cat the most. However, the system is clearly designed to burn SOME oil, per the PCV system. The question is, how much more can it tolerate?

Be sure to post some results data!

I've been using 1:132 (1 oz per gallon) used oil mix in my motorcycle for years. I swear it runs smoother with it's marginal carburetion at idle. The oil is filtered by gravity through a fuel filter before going into a bottle and added to the tank before filling for a good mix.

The motorcycle has a 10.2:1 compression so much more than that reduces octane rating too much, your vehicle will be different so experiment to see what your engine can tolerate. At the rate I use the used oil, I burn all the oil from the previous change by the time the next oil change comes around - why waste it?

Because oil has such a high flash point, I wonder how much is burned and how much is just vaporized and sent out the tail pipe. That's another discussion though.

Good idea using it in diesel. I'll mix some into the tractor diesel.

Could probably mix 15% into E85 and get it to run. Could probably make an exhaust heat exchanger to get it very hot, and mist it into the intake along with steam and it wouldn't burn too bad...

Could probably wait 5 years until I get round to making my "universal carburettor" concept that's an on car oil refinery and will run on anything from hot candle wax to convertor gas.

You can tell when an engine is burning even a small amount of oil, because it doesn't burn very well, at best most of it is turning in to soot in the exhaust system, motor oil has alot of additives in it that are designed to keep it from burning, recycling the oil is just that, recycling it in to new oil, separating out the grit and water, neurilzing the acids, and adding more of the additives that get used up as the oil ages, it seems like a great idea.