MinisterofDOOM wrote: ↑

Mon Jun 22, 2020 9:20 am

There are multiple advantages with older cars. With newer cars, it's a non-issue. Before ethanolized gas became common, ethanol was a common occasional fuel additive to clean moisture out of gas tanks, since it's hygroscopic.

For those of us with MUCH older cars, and those of us with moderately old cars, ethanol has some downsides. But it also has potential upsides for the right applications.
1: Ethanol is very hard on certain types of rubber, which are often used in fuel lines, gaskets, seals, etc. For instance: carburetor gaskets. It oxidizes them and causes them to become brittle and porous, which of course leads to leaks, and tiny chunks in the fuel system.
2: Ethanol is hygroscopic. It will absorb moisture not just from the fuel tank, but from the air. If you have an older (e.g. non pressurized) fuel system with ethanolized fuel sitting in it, it'll suck up ambient moisture just like brake fluid will. This can then end up sitting in undesirable places like rubber lines, at gasket seats, etc. Not much in a fuel system is iron or steel, so corrosion isn't really an issue. But some car manufacturers did make unwise decisions with injectors in the 80s and 90s. Like Nissan. If you have something that's going to sit seasonally (summer car, snowblower, mower, etc.) make SURE you use fuel stabilizer or better yet non-ethanol fuel and fuel stabilizer. Otherwise you might enjoy a premature carb rebuild after a few seasons when the diaphragm or gaskets start eroding.
3: Ethanol contains less energy per volume than gasoline, but is also harder to combust (more knock resistant). This means it's "higher octane" and fuel mixes will reflect this. "91 octane" E10 is actually probably lower than 91, but the ethanol raises the effective octane. So it's great for modern high-compression cars, boosted cars, and especially direct injection cars with high combustion chamber temps.
4: The detonation-resistance more than offsets the lower energy content compared to gasoline, you can run higher compression with E85+ than with gasoline, which is why ethanol is a popular race fuel.
5: It keeps the corn farmers in business and is an example of the monumentally twisted modern state of lobbyism and government overreach.
6: Because people think it's better, it generally sells for a premium, which is stupid. But then Ethanol is cheaper than gas, so hey at least we're not paying a premium for a cheapskate diluted mix with E10, right?
7: It's debatably "cleaner" to burn.
8: Any car with a modern EFI system using oxygen sensors will detect the ethanol mix and adapt to make any mix work, so there's no reason to run one particular mix over another unless you're getting lots of timing retard for knock prevention. But modern cars don't even really work that way anymore (stratified injection and all that crap) so you might as well just buy whatever's cheapest. Don't even worry about detergents anymore, since direct injection bypasses the intake port and you lose out on one of the primary advantages there.
9: It's volatile (chemistry sense, not "explosive) and is thus used as a combustion chamber temp control measure. MEthanol is often used in modded diesels to lower temps for this reason. Ethanol is also used in rare cases. Keeps temps down and allows higher compression with more even burn.