Adelaide, whom I’ve mentioned before, really goofed this time…
Yesterday, her car ran out of gas. She had a can of fuel in the trunk, and poured it into the fuel intake. The car started, but stalled. It turned out she had taken it from her brother Bill’s gardening truck. Some of his motorized equipment comes with 2-cycle engines which, of course, take a mixture of gasoline and oil in the fuel tank. An automobile regularly has a 4-cycle engine and can’t run on 2-cycle fuel. The mechanic who checked the engine said the fuel filter will have to be cleaned–and I figure the fuel tank will have to be drained and cleaned out. Is there a potential for serious damage inside the engine (a '97 Nissan) itself?
It will run, but it might smoke from burning oil. Just drive to the gas station and fill it up to dilute the fuel oil mix.
I’m not a mechanic but the fuel to oil ratio for a 2 cycle is generally not higher than maybe 12 parts petrol/gas to oil. Here’s a sample chart. You can see it goes much higher in many cases.
So my guess is that it’s probably no worse than having a car that burns a little oil - depending on what she actually used and how far she drove.
I wouldn’t pull out all of the stops with the “repair” if the car is running well, but that’s my uneducated, pulled-from-twixt-mine-ass-cheeks opinion. I suspect that just diluting what’s in the tank is probably all you need to do.
If I’m wrong about that, other parts that could be affected would be the spark plugs - might get fouled. Could have some impact on the catalytic converter, although it IS designed to deal with partially burned hydrocarbons. If the car has a carburetor, that might be an issue - don’t know how different the venturi jets are between a 2 and 4 cylinder or if oil could affect other things like plastic components, gaskets, etc.
The engine stalling has nothing to do with whether the fuel is mixed two-cycle fuel or straight gas. If she ran the car out of fuel, and tried to start it with an empty tank, she MAY have destroyed the bearings in her fuel pump. Most fuel pumps are lubricated by the fuel in the tank. (side rant) Always keep your fuel tank AT LEAST 1/4 full, your fuel pump will thank you for it (end rant). When she tried to start it with an empty tank, the fuel pump did not get lubricated. If she ran the fuel pump for many cycles while trying to start the car, she MAY have destroyed it.
If she had crud in the bottom of the fuel tank sump, when she added the fuel it could have stirred up this crud which got sucked up by the fuel pump and sent to the filter, plugging it. This would be my guess as to what happened.
" An automobile regularly has a 4-cycle engine and can’t run on 2-cycle fuel." Not true!
As far as running a car engine on two-cycle gas, I always run two-cycle gas in all of my small engines. This “new” gas with all the alcohol in it does not lube the valves as well as the “old” gas did. This is important for air cooled engines. The two-cycle oil lubes my valves and they do not get stuck on my engines. I do have to clean my spark plugs more often though.
As the OP’s sister did, I have used two-cycle gas in my pickup when I have run low on fuel for it. As has been said, it just smokes a bit until I fill my tanks with straight gas. I beleive that the catalitic converter will not stand up to a steady diet of this fuel, but a one time use should be OK.
Are you SURE that the fuel she used was two-cycle gas?? If it was DIESEL fuel, then no, her car will not run on that. However, after cleaning the fuel lines, filters, and injecters or carborator of the diesel, just fill the tank with regular gas and she is good to go. It will smoke for that tank and clear up after that. Once again no need to pull the tank. BTW diesel is an oil, it will lubricate the fuel pump. I do not know what, if anything, it will do to the catalitic converter.
All of this ASSuMEs that she only put in two gallons or so. IHTH, 48Willys
I think spark plugs might need replacing due to carbon buildup, but am not sure. If so, it isn’t much expense.
The woman in the OP is not my sister. Her brother is a professional lanscaper, whom I have known about as long as I have known her. She has an unfortunate tendency to take things without asking. 
Does it really get destroyed this quickly? If the engine won’t run, it’s because there’s no fuel pressure - which means the load on the fuel pump is nearly zero. In addition, even if the pump is sucking in air, there is still a residual quantity of fuel in the pump, similar to the way that engine oil continues to coat engine parts for some time even if the oil pump isn’t running.
With no pumping load on a pump operating with fuel-wetted (if not completely immersed) parts, I suspect you’d have to run it for a very long time to damage it so badly that it couldn’t create enough pressure to run the engine later on when the tank is properly full.
Or am I wrong? Are there in fact known cases where running a tank to empty has resulted in fuel pump damage? I’d be interested to hear from a professional mechanic who has personally witnessed vehicles that were run to empty and then needed their fuel pumps to be replaced.
The fuel pickup in the tank should have a coarse-mesh sock on it that prevents large quantities of particulates from getting sucked up. It’s possible that got clogged with coarse sediment stirred up by a sudden inrush of fuel into a virtually empty sump, but the vehicle would have to have had a history of being fed filthy, badly contaminated gas for a long time. I had a motorcycle that I ran for 135,000 miles (fuel consumption comparable to an economy car), and I replaced the in-tank filter every 24K miles just because it was called for in the maintenance schedule. During those replacements I never observed any sediment in the tank or on the pickup sock. You’d pretty much have to manually pour in a handful of silt to get the kind of insta-clog action you describe.
" An automobile regularly has a 4-cycle engine and can’t run on 2-cycle fuel." Not true!
As far as running a car engine on two-cycle gas, I always run two-cycle gas in all of my small engines. This “new” gas with all the alcohol in it does not lube the valves as well as the “old” gas did. This is important for air cooled engines. The two-cycle oil lubes my valves and they do not get stuck on my engines. I do have to clean my spark plugs more often though.
As the OP’s sister did, I have used two-cycle gas in my pickup when I have run low on fuel for it. As has been said, it just smokes a bit until I fill my tanks with straight gas. I beleive that the catalitic converter will not stand up to a steady diet of this fuel, but a one time use should be OK.
Are you SURE that the fuel she used was two-cycle gas?? If it was DIESEL fuel, then no, her car will not run on that. However, after cleaning the fuel lines, filters, and injecters or carborator of the diesel, just fill the tank with regular gas and she is good to go. It will smoke for that tank and clear up after that. Once again no need to pull the tank. BTW diesel is an oil, it will lubricate the fuel pump. I do not know what, if anything, it will do to the catalitic converter.
All of this ASSuMEs that she only put in two gallons or so. IHTH, 48Willys
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In the fall, I like to dump out whatever small volume of gas I haven’t burned in the mowers/weedwhackers. I do this by dumping the gas in my car’s full fuel tank. Hasn’t caused any problems I’ve noticed.
A car that gets 30 MPG and burns a quart of oil per 1000 miles is basically running on the equivalent of a 133:1 mixture, which is well off of the bottom of the chart. However, I still wouldn’t expect the two-stroke mix that she poured in her tank to foul the plugs - otherwise one might expect it to foul the plugs in whatever two-stroke engine it was used. This is especially true if she only poured in a few gallons of two-stroke mix.
1997 model year, the car is almost certainly fuel-injected. The cat is designed in part to deal with hydrocarbons, but two-stroke oil is not designed with cat compability in mind. It may have high levels of ZDDP or other additives which could prematurely poison the cat. The only way you’d know for sure is if the MIL (“check engine” light) lights up or if the car fails an emissions test; if not, then there’s not much point in investigating that any further. In any event, this would not have caused the car to stall.
Back before I hired a lawn service, I’d dispose of my old 2-cycle oil at the end of each season by dumping it into my pickup. And it’s not some old-timey junker with a carburetor- it’s a 2005 computer-controlled, fuel injected modern engine. No harm done- it gets diluted with the other gas in the engine.
About all I can think of is that possibly when her car was out of gas, putting in a gallon of 1:50 2-stroke gas might have caused some sort of crud to build up on the O2 sensor and causing the car to stall. That’s unlikely though; it should have fallen back into open mode and just run inefficiently (i.e. by ignoring the O2 sensor).
I think it’s far more likely that Adelaide’s brother’s gas can was full of all sorts of trash and crud that probably completely clogged up a partially clogged gas filter. That seems like a far more likely reason for the fuel filter replacement and stalling to me. The 2-cycle oil shouldn’t have done that, I think.
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I am an aircraft mechanic, so I guess I qualify as a “Professional Mechanic”. By definition, since I get paid to wrench on things, I am a “Professional Mechanic”.
I have had to replace fuel pumps on vehicles (not aircraft) that have run out of fuel. Note, it is always in a vehicle that has consistantly run on the bottem 1/4 of the tank, Hence my rant.
As you have experianced, most folks buy fuel at a reputable station. They rarely get “crud” in their tanks. However if the fuel is frequently obtained at a “cut-rate” station, it often contains more contaminants the the “good” fuel. My tanks are also very clean.
Four cycle plugs are usually “colder” then the plugs for two-cycle engines. The four cycle engines will not burn off all of the excess oil with these "colder’ plugs. If I ran “hotter” plugs in my four cycle engines, the oil would burn off, but I run the risk of burning a hole through my pistons, BAD, VERY BAD!!
dougie_monty, My mistake, I misread the OP.
kayaker, You said “In the fall, I like to dump out whatever small volume of gas I haven’t burned in the mowers/weedwhackers. I do this by dumping the gas in my car’s full fuel tank. Hasn’t caused any problems I’ve noticed.”
A common practice. The two-cycle oil has someting like STA-BIL in it. In THEORY the fuel SHOULD be good for over one year. In practice what you do is cheap insurance. I use two-cycle fuel year round, so I do not do this.
As bump stated, “I think it’s far more likely that Adelaide’s brother’s gas can was full of all sorts of trash and crud that probably completely clogged up a partially clogged gas filter. That seems like a far more likely reason for the fuel filter replacement and stalling to me. The 2-cycle oil shouldn’t have done that, I think.”
Yes, I agree.
AHAHAHAHA!!! That’s pretty funny. I mean, I’m sure you’re right and all that. I was just thinking of some of the beaters I’ve driven that essentially had intravenous lines of 20Winfinity hooked up to the engine just so they could get some compression.
Damn. Have to go change my shorts now. 
I’ve done this before when I was low on gas. Never even considered that a bit of oil in the gas would harm my car, and so far it never has.
The car is not a '97 Nissan. It’s a '98 Honda.
I retrieved the keys and tried to start the car this morning. It turned over but wouldn’t start. I called the Auto Club and had it taken to my mechanic. who knows the owner (Maureen, whose daughter Adelaide was driving it when it ran out of gas. Bill is Adelaide’s brother.)
Yeah, 1 quart of oil per 1000 is not gawd-awful; I think that’s generally regarded as the limit at which a service manual typically suggests that the problem needs to be fixed. As you’ve noted, that doesn’t mean an engine won’t continue to run even with much higher oil consumption than that.