Ethanol

For me I used to just buy the cheap gas. Then I moved to Idaho and gas was cheaper and getting premium really wasn't much more. So I started using 91-93 octane gas with 10% ethenol. So when I was younger I was so picky about my cars. I would change spark plugs and wires put some octane booster and spray out the throttle body every oil change. I'd always notice carbon build up inside or under my throttle plate. But when I sit he'd to the premium I noticed it would be cleaner and I didn't have to spray the tb anymore. I really don't add octane boosters any more either.
When I got the 76 dart I ran premium until I noticed the next town over had non ethenol 91. So I used it a few times and noticed my car has a little more responsiveness to it and it doesn't smoke as bad. Currently I am Getting ring blow by. So it already smokes til I pull the motor soon. But it does t shoot so much black smoke when Starting and really doesn't shoot much while smoke when warmed up Compared to when I'm stuck using ethanol. Now normally you wouldn't see it like this last mentioned but it did show me when I get the block finished up that no. Ethenol looks to burn a little cleaner and gives a tad bit more power. It won't turn your old school I to a muscle car but your motor will be happier.
As for the plastic part lol have you looked under the hoods of cars I. The last decade? Lines and tanks all plastic. Can t find prepmade metal lines for my 91 sanoma instead I have to make my own with large brake line