Just bought a new used car and the previous owner only ever used 95 octane in it. It's a 2012 Forester, is there any reason I should keep up with the 95 or is 91 ok?
Thanks
Swapping from Regular Use of 95 Octane to 91?
wittyusername on 10/04/2020 - 14:04
Comments
Read the manual. It will specify whether higher grade fuel is necessary. Some more finely tuned engines will specify 95 or 98
Use whatever fuel is recommended in the user manual. Don't use anything lower than that. Anything higher than what's recommended will only give you marginal benefits in a naturally aspirated car.
Like previous posters mentioned, the manual should say. You can also google what other forester owners run. Do you have the 2.0l turbo or 2.5l n/a engine? The 2.0l turbo engine will benefit more than the 2.5l will running 95 octane. The 2.5l 'may' be fine with 91 octane, you would need more information on the specific engine.
The fuel door should have said what type of fuel.
Legends, thanks all. I'll double check tomorrow when I'm sober.
From the Subaru Forester owners manual;
Fuel:
Non-turbo models
Use only unleaded gasoline with an octane rating of 87 AKI (90 RON) or higher.Turbo models
Use premium unleaded gasoline with an octane rating of 91 AKI (95 RON) or higher. If premium unleaded gasoline with an octane rating of 91 AKI (95 RON) is not available, regular unleaded gasoline with octane rating of 87 AKI (90 RON) or higher may be temporarily used. For optimum engine perfor- mance and driveability, it is required that you use premium grade unleaded gasoline with an octane rating of 91 AKI (95 RON) or higher.So if it’s turbo, use 95. If not 91 is fine.
It seems so… if only there was somewhere we could look up this information… like a booklet that comes with the car would be a great idea…
Was more wondering if the decrease in fuel quality would affect it if it's only ever had 95.
@wittyusername: It's not really fuel quality, it's knock rating. Very generally… Boosted cars are more prone to precombustion (knock), but it's also affected by ignition timing…more advance can increase power, but also knock. Some engines have knock sensors so can retard the timing if lower octane fuel is used.
@OzzyOzbourne: Yeah they're advertised by an octane rating. I think they also differentiate their fuels by further filtering, and using additives. So there may be other 'benefits' to paying for the 'premium' fuel, than just the octane.
eg
"91RON is mandated to include no more than 150 parts per million of sulphur, which burns in the combustion chamber and is emitted in particles that contributes severely to urban smog and respiratory illness. Meanwhile 95RON/98RON are mandated to 50ppm."
If your car has learned to like the good stuff it’s going to get stroppy if you suddenly start giving it inferior home brand stuff.
No it won’t, it won’t care at all.
Sorry, forget the sarcasm emoji.
Oops. Did it again.
Well, some people actually believe it will, so hard to tell if someone is serious or joking.
Your car won’t suddenly create more compression just cause you use 95 over 91.
just curious, does anyone use E10?
Only to refill rental cars
oh ok
just curious, is there a reason why dont fill personal car with E10?
Depends if the car can run it, you need compatible fuel lines to run ethanol (it breaks down rubber). I'm not sure if that holds true for low ethanol content like e10 (10% ethanol).
It has other funny properties too. If it sits long enough it will absorb water content. It's more difficult to start a cold engine on ethanol. You consume a greater volume of ethanol to produce the same energy (power) output. It has a significantly higher octane rating compared to petrol, and significantly lowers combustion chamber temperatures.
So for race cars its perfect, most of those factors won't matter for a track car. I run e85 (85% ethanol) in mine.
For an every day car, depends how much those factors really affect your experience with the fuel (I haven't tried e10 myself).
Misinformation and stupidity. E10 is not a replacement for 91 that so many people compare it to, it’s more a replacement for 95, as their RON are closer.
Then there are the (fropanity) heads that will claim that they get 250 less km per tank on E10, it turns to sludge, it eats hose lines, it’s 30%water out of the storage tank, it’s 20% less power, etc etc, which simply isn’t true.
There are numerous threads on here already about E10 and the ensuing regurgitating of misinformation by the retards that heard something from the mate of a mate who knows a guy who was a mechanic 28years ago…
If you want to know if your vehicle will run on E10, get on your car manufacturer’s website and they will have the information you are looking for.
@pegaxs: Once you’ve checked if your car can safely use it, then do your own tests. Check the actual fuel consumption and compare t to regular unleaded or 95 if you must. Don’t trust your seat of the pants measure, actually measure it over a few tanks. Seat of the pants ‘running better’ doesn’t mean much either as your perception is flounder by the fact you’ve been told it’s better and you paid more for it.
My experience says that driving style makes a bigger difference than fuel type.
@Euphemistic: And should have added there wasn’t a noticeable performance gain or any noticeable change in how the engine was running.
I did measure fuel consumption over a few years using several tanks of each kind and found no measurable difference in the figures that couldn’t be explained by driving conditions. Ie more highway than usual or using the AC etc. the car was suited to standard unleaded (and was a forester, but 2003).
@pegaxs: My 2002 mazda 323 definitely did less km when i filles the tank with e10. Not 250k less but definitely about 5-10% less.
@nikoris: And of course you had this measured under scientific conditions in a controlled environment.
Yep my FJ Cruiser has E10 as recommended fuel both in the manual and sticker inside the fuel filler door. Never had an issue and don't notice any remarkable difference with premium fuels.
91 is OK. Any higher octane than than that may be wasted.