QUESTION - How does ethanol mixed with petrol affect my engine and fuel system? Or Lions, tigers and ethanol in my gas! Oh my!!
ANSWER - In an attempt to reduce American dependence on foreign oil, American petrol is being mixed with 10% ethanol and they are talking about adding 15% for newer cars only. It is difficult to find pure petrol anymore as 10% ethanol has become the "standard" blend. So how does it affect us driving old engines that were designed and built back in the old days when petrol was just pure gas with very few additives?
Ethanol works as a solvent to wash away lubrication. This is bad for cylinder walls, piston rings, valves, valve guides and fuel system components. Also, ethanol is nasty about drawing moisture into your fuel system and causing corrosion. The higher the ethanol content, the worse the problem. This of course means that your engine doesn't last as long between rebuilds or needing valve job and likely valve guides replaced.
The only way I know of to counteract this is with a fuel additive that has lubricating properties specially designed to add lubricating protection to these components. I think the best of these additives is Marvel Mystery Oil. Marvel Mystery Oil replaces that lost lubricity and reduces the wear on the engine. Adding the recommended amount to each tank of ethanol blend counteracts the ethanol.
Another problem with Ethanol blends is that the ethanol attacks older rubber fuel lines and many plastics commonly used in fuel systems. If you have replaced your original fuel line with a rubber fuel line years back chances are you have had blockages from little chunks of rubber coming lose inside the fuel line walls. Thankfully this is an easy fix as fuel line manufacturers recognized the problem early on and changed their fuel line rubber formulation to compensate. So if you have been seeing tiny black particles in your see through fuel filter all you need to do is replace all your fuel lines with new fuel hoses.
Replacement Zenith carburetors come with a plastic fuel float that does not stand up to ethanol. Best bet is to reuse the float from your factory original Zenith. Old electric fuel pumps that use a plastic diaphragm could also have problems. If you have an old one, it probably would not hurt to carry a newly manufactured spare pump and any tools needed to replace it alongside the road. The diaphragm in your old electric pump may or may not be susceptible to ethanol but it doesn't hurt to be prepared. Perhaps that’s one reason some older car manuals say, “Don’t use gasohol.” (Newer car engines are supposed to be designed to cope with ethanol being a major component of fuel).
Also, the introduction of the ethanol also reduces fuel efficiency, for which there is no “solution.” The laws of physics dictate that burning a gallon of ethanol only gives about 2/3 the energy that burning a gallon of gasoline will give. Ethanol, CH3-CH2-OH, has an O (oxygen) already chemically combined in it; so, relative to gasoline, which is hydrocarbons—just C’s and H’s—ethanol is, roughly speaking, “already partly burned.” So I wouldn't expect much in the way of improved fuel economy from any fuel additive. So no matter what you try, your fuel mileage isn't what it used to be before 10% ethanol blend became the standard mix.
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