Saw a guy posting on Reddit this morning saying that he did 12 tanks of gas through his Honda acti and he found that he got the best gas mileage out of 89 octane. So got me to think what would be the best gasoline for our Subarus, right now I'm running a 93 octane that has ethanol in it because the non-ethanol pump is like 45 minutes away from me. I plan on using non-ethanol gas in the future, but I think that's probably in the upper 90s of the octane rating as well too. If anybody got any experience for recommendations let me know. https://www.reddit.com/r/keitruck/c...line/?utm_medium=android_app&utm_source=share
Whatever is cheapest. I saw No difference from vp, clear gas to Chevron or shell nitro+ Didn't have any experience with e85 but I'm not sure what it would do to the fuel lines anyways.
How much money do you want to spend? That one. I don't think even the supercharged engines are going to be pushing enough to really warrant spending the extra coin on higher octane stuff. If your vehicle sits a lot, be careful with stuff that has a bunch of ethanol in it. It'll eat rubber hoses/seals and crap.
I think this way: octane additive is a pre-ignition inhibiter to make fuel "burn" a bit less spontaneously. If an engine has less compression, ignition advance or work load and can run without knocking it will convert the fuel into motive energy more effectively on lower octane. All else given as equal I do find I get best economy on lowest octane a particular vehicle can tolerate.
I wouldn't worry about ethanol at the 10 or 15% level other than if it sits a long time between running make sure it has a stabilizer added to it. As to the octane, I find the F6A in my Joypop wants the 93 octane and I can really tell the difference on performance to the 87 octane.
The supercharged version CR is roughly 8.3:1 so a mid grade gas of 89 would be good. Premium would not warrant any added performance benefit.
Another positive for ethanol free gasoline is the total energy content per unit of volume is higher ( see: https://www.eia.gov/tools/faqs/faq.php?id=27&t=4 ) by about 3%. A small improvement but along with being more friendly to our older fuel systems that may be driven less frequently. A major convenience store chain just a few miles across the MD/PA line from me has dedicated e-free pumps, rated 90 octane at a price point of about $0.50/gal over regular 10% e-unleaded.
Reference: There are only two types of Japanese petrol in general circulation. One is regular gas and the other is premium gas. Here in Japan, premium gas is called hi-oku (high-octane) gas. According to the Japanese Industrial Standards (JIS), regular gas is defined as RON 89 or higher, and premium gas is defined as RON 96 or higher. The actual RMS values available are as follows Regular Gas; RON91, MON83, AKI87 Premium Gas; RON100, MON89, AKI94.5 Different nozzles are used for each type of oil. Nozzles are not shared among different types of oil. I think AKI87 gas is sufficient for older kei-cars that have not been modified.However, only Subaru's DOHC supercharger is for premium gas only (regular gas use is strictly prohibited). Here in Japan, gases such as E10 and E85 are not distributed; both ETBE (mainly bioethanol and methanol additives) blends are less than 3%, and the actual blending rate is less than 2%. An aside: On rare occasions, quirky vehicles are sold in Japan exclusively for premium gas. In the past, vehicle fires have occurred due to the use of low-AKI gas, and this story is well known to those involved. Examples, TOYOTA CELICA TRD SPORTS 202HP, TOYOTA Vitz (Yaris) Turbo TRD Ver. 148HP
My 1993 carb version enjoys drinking half regular 89 octane with 10% ethanol, and half clear gas at 91(?) octane. The clear gas is certainly more efficient, but its also $0.50 more a gallon, so... I feel this blend is the best of both worlds and more closely resembles the low ethanol gasoline produced in Japan. I did tweak the fuel delivery down a bit as it was running rich, but that may be attributed to the fact that the truck was running at sea level and I'm located at around 2200 feet. I also cleaned out the throttle body and carburetor with some carb cleaner and put in some Gumout to prevent deposits. Runs like a BOSS now. Have an issue with startup I believe might be related to the check valve in the fuel pump, so I just turn the key twice to actuate the pump and it starts reliably. I will test the fuel pump and system to fully diagnose when I get a chance.
