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Old 06-10-2013, 12:55 PM   #1
Mark R
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Default Use rubbing alcohol as injector cleaner and decarbonizer?

Has anyone tried this?

It sounds like it should work quite nicely. Rubbing alcohol (isopropanol) is cheap and readily available. It is a very high octane fuel (octane rating approx 120), so shouldn't lead to detonation.

Unlike ethanol/methanol, it is a secondary alcohol so has minimal corrosion concerns as it is a much weaker solvent and cannot be oxidized into acids, like the others. While many car manufacturers do not recommend (even if they will warrant their vehicles for use with higher concentrations) the use of ethanol concentrations of higher than 5%, much higher limits tend to be specified for IPA.

While an oxygenate, it will lean out the mixture, but it is a weaker oxygenate than ethanol (IPA is 25% oxygen, eth is 33% oxygen and Meth is 50% oxygen), so can be added in larger quantities. Due to its high hydrogen content, and large bulk, it will also lower the total energy content and lower heating value of the fuel, lowering combustion chamber temperatures.

Perhaps, additional cleaning could be obtained by adding water as an additional solvent. IPA has the property of making water completely miscible with gasoline, up to water levels of nearly 35%. The additional water in such a mixture, should further lower combustion temperatures, help to dissolve additional fuel system contaminants, clean valves, etc.

I've heard of this tested once on an old lawnmower with a major carbon problem - tank was filled with 50% gas, 50% rubbing alcohol (70%). Ran fine, but perhaps not quite as powerful. At the end of the tank, the head came off, and it looked like someone had steam cleaned the engine.

So, what do people reckon to my idea of sticking a gallon or 2 of 90% IPA into a half-tank of gas? Do you reckon this will do any good?
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Old 06-10-2013, 01:09 PM   #2
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I reckon you should't dump rubbing alcohol in your gas tank. I think it won't do crap and who knows what the hell it might break in the fuel system.
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Old 06-10-2013, 01:17 PM   #3
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Plastics don't react well to rubbing alcohol. If you know you have no rubber/plastic anywhere in your fuel system, it's probably safe.

I don't think I'd do it.
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Old 06-10-2013, 01:40 PM   #4
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^

Might be ok if the car was oked for E85, but even then why? F/I's rarly get "dirty" at the fuel point. And if you want to decarbon the intake/comb chamber then just suck the cleaner through the PCV hose or other vacuum line.
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Old 06-10-2013, 01:55 PM   #5
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Given that some (most?) gasoline is 10% alcohol already I don't think you'll be doing anything special.
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Old 06-10-2013, 03:14 PM   #6
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Quote:
Originally Posted by Mark R View Post
Has anyone tried this?

It sounds like it should work quite nicely. Rubbing alcohol (isopropanol) is cheap and readily available. It is a very high octane fuel (octane rating approx 120), so shouldn't lead to detonation.

Unlike ethanol/methanol, it is a secondary alcohol so has minimal corrosion concerns as it is a much weaker solvent and cannot be oxidized into acids, like the others. While many car manufacturers do not recommend (even if they will warrant their vehicles for use with higher concentrations) the use of ethanol concentrations of higher than 5%, much higher limits tend to be specified for IPA.

While an oxygenate, it will lean out the mixture, but it is a weaker oxygenate than ethanol (IPA is 25% oxygen, eth is 33% oxygen and Meth is 50% oxygen), so can be added in larger quantities. Due to its high hydrogen content, and large bulk, it will also lower the total energy content and lower heating value of the fuel, lowering combustion chamber temperatures.

Perhaps, additional cleaning could be obtained by adding water as an additional solvent. IPA has the property of making water completely miscible with gasoline, up to water levels of nearly 35%. The additional water in such a mixture, should further lower combustion temperatures, help to dissolve additional fuel system contaminants, clean valves, etc.

I've heard of this tested once on an old lawnmower with a major carbon problem - tank was filled with 50% gas, 50% rubbing alcohol (70%). Ran fine, but perhaps not quite as powerful. At the end of the tank, the head came off, and it looked like someone had steam cleaned the engine.

So, what do people reckon to my idea of sticking a gallon or 2 of 90% IPA into a half-tank of gas? Do you reckon this will do any good?


1. Bullshit unless you can document this. 10% ethanol is, as far as I've seen over the last couple of decades, perfectly "fine" as far as warranties are concerned from every vehicle manufacturer that sells in the U.S. Have yet to see one car company declare that use of 10% ethanol gas voids any warranties. Now, using higher concentrations in vehicles not designated something like a flex fuel vehicle will do that, but 10%? Nope.

Prove it.


2. You do realize that IPA, or isopropryl alcohol, has been used in auto gas additives for years upon years. Ever heard of HEET or other additives claiming to remove/dry your gas? IPA is its active and primary ingredient. The big advantage to IPA is that it's distilled/refined from oil unlike ethanol, which is a fermented grain product.
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Last edited by Meghan54; 06-10-2013 at 03:27 PM.
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Old 06-10-2013, 03:41 PM   #7
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Diluted E85 works well for getting old beaters to pass a sniffer test. Not going to hurt anything if you don't overdo it. And I use a small amount then fill it up with normal gas afterwards.

As injector cleaner? Not terribly useful. Alcohol sucks for hard deposits, and gasoline works good for general grime. Plus the possible issues with rubber/plastic parts not designed for high alcohol content, plus the amount you're going to lean out the engine. The risks aren't huge, but neither are the benefits.

I wouldn't bother with any injector cleaner that doesn't involve hooking a pressurized source directly to the fuel rail.
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Old 06-10-2013, 04:23 PM   #8
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Quote:
Originally Posted by Mark R View Post
I've heard of this tested once on an old lawnmower with a major carbon problem - tank was filled with 50% gas, 50% rubbing alcohol (70%). Ran fine, but perhaps not quite as powerful. At the end of the tank, the head came off, and it looked like someone had steam cleaned the engine.
Similar water test (pdf). Perhaps just driving in high humidity conditions has some effect.
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Old 06-10-2013, 04:53 PM   #9
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Quote:
Originally Posted by Meghan54 View Post
1. Bullshit unless you can document this. 10% ethanol is, as far as I've seen over the last couple of decades, perfectly "fine" as far as warranties are concerned from every vehicle manufacturer that sells in the U.S. Have yet to see one car company declare that use of 10% ethanol gas voids any warranties. Now, using higher concentrations in vehicles not designated something like a flex fuel vehicle will do that, but 10%? Nope.

Prove it.
I didn't say that vehicle manufacturer's would void warranties for the use of E10, all manufacturers selling cars in the US, warrant the cars for E10. That does not mean that the manufacturers like it.

Many of the European manufacturers do not recommend the use of E10 in their vehicles, at least in Europe. It is because of this that the EU specifications for "normal" gasoline specify a maximum of 5% ethanol. There has been a big push by "big bio" to get this boosted to 10%, but the car manufacturers have managed to get the politicians to resist for the time being.

A number of manufacturers are on record as part of these discussions as saying that even E10 is potentially problematic. Of course, it could be because they want to cheap-out on seals and hoses for the Euro models, and they've got bigger checkbooks when it comes to lobbying.
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Old 06-10-2013, 05:13 PM   #10
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Similar water test (pdf). Perhaps just driving in high humidity conditions has some effect.
I would strongly suspect that all the rubbing alcohol is doing is suspending the water in something fairly volatile. Isopropyl, IIRC, is 15% water at it's most potent, and typically more like 25%. But since water likes alcohol, and alcohol mixes fine with gas (whereas gas and water don't get along so great)...it's probably just a means to an end, no? The steam is doing the work, but that pesky fuel with ~2/3 the energy content of gasoline, plus the accompanying inert water, is not something I would want to use in large quantities.

The better route, if you really want to clean valves and combustion chambers, would be an IV drip of water through a vacuum port. I've got a plastic one somewhere, still in the package. Pretty much just like you'd picture an IV, with a reservoir that hangs underneath the hood and a vac hose with a little inline dripper. It came from some company that sold their own cleaner, which I suspect was probably just water and a compatible solvent. Smells like shit.
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Old 06-11-2013, 06:45 PM   #11
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Well, this plan is off. I was planning to try this on my lexus IS250 which I'm sure has a carbon problem.

Anyway, I've just checked the VIN and engine numbers with lexus in their compatibility database. My vehicle is not even E10 compatible. It was one a few hundred cars which used a non-ethanol compatible fuel system.

Thankfully, E10 isn't used where I am, yet. But, the lack of compatibility even with E10 is a bit worrying.
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Old 06-11-2013, 07:04 PM   #12
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Why risk it? Seafoam works well and won't ruin anything..
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