Hi, I drive a 2011 subaru forester x 2.5l with 400km highway round trip every second or third day.
At the moment I'm just filling up with 91,thinking to save money, as I do go through fair bit of fuel every week. Also, the car manual mentioned
2.5l engine only need octane 90+, not 95+.
I guess the big question is, will 95 actually give me more mileage,considering I usually drive 110 km/hr consistently, and hardly do any "start stop" driving.
Well, like you said, most link will just say up to you only.. Which is rather confusing.. Thought I'll get general opinions from drivers in the forum..
What does the owners manual say?
If it says 91, then there will be no benefit using anything higher.
If it says 95, use 95.
95 isn't better than 91.
If your engine needs it, use it.
If it doesn't need it, don't use it.
As the car only requires 91 RON or higher, just put in 91 RON. You may see marginally higher mileage with 95 RON but the higher cost per litre will make this not worth it.
MAYBE!!!!
Also, the car manual mentioned
2.5l engine only need octane 90+, not 95+.
Looks like you answered your own question.
Depends, Australia uses RON and America uses AKI (RON+MON/2).
90 AKI is around 95 RON.
Also there is no 90 in Australia, we have 91.
Being a Subaru, they usually do need 95.
Just try the 95 and see if it makes a difference.
Cheers
and report back
An engine's octane requirement can be found in the vehicle's handbook. However, a fuel with a higher octane number than required will not necessarily produce noticeable benefits.
i'm currently doing the experiment myself, done about 6 tanks of a new car, will swap and do another 6 with different RON
This is good advice.
You will be the expert on your car and driving patterns.
Spoiler alert. The RON makes no difference to mileage unless your car is designed to run 98 and your using 91. If your car is designed to run 91 and you put 98 in it, you’re just burning money.
You will get inconsistencies in your data doing it this way. Every trip you take is different. Weather, humidity, pressure, tyres, passengers, stop signs, idle time, air con, speeds, time of day.
An example, I always fill up at the same servo, using the same fuel type. I do the same drive to work every day and the same drive home, traffic is different, weather is different, number of people in the car is different. My full tank distance can vary up to nearly 100km on any given tank.
So, how you can attribute what is fuel related and what is external factors is beyond me. You can say it’s down to the fuel, but I’ve given you half a dozen reasons why it isn’t.
I'm going to wait until our resident mechanic answers before I express my opinion. Over to you pegasx…..
I just shake my head now at RON talk. For some reason, people think 98 has “moar power!!” When it doesn’t. It just has additives in it to resist knock. That’s all…
I try and educate people and all I cop is “yeah well, how come my Civic gets 600km on 98 and 450km on 91…” when that simply isn’t true. There is no convincing people of what octane rating means. And it seems that almost everyone on OzB has some of the most high tech “butt dynos” available…
Use the petrol that is listed in your manual.
99% of dumb questions like this can be solved just by reading the manual.
<^>
I drove my car on 95 for 5 years since new. Then switched to 91 for 3 years. No noticeable mileage improvement with 95, so it’s been a waste of money for me.
Highway or town?
No.
There is less specific energy in higher octane fuels. Use the octane rating your car was designed for.
Less energy = worse fuel economy.
It is only a couple of dollars more to fill with a higher octane. If doing so makes you feel special keep doing so. Both coffee and beer are far more expensive!
Just test it yourself. Record 3-4 tanks in a row of each and compare figures. Record it accurately, not adjust km to a tank full, but actual L/100km, try to keep you driving situation the same too (ie don’t include hours of town traffic if you normally spend your driving on the highway). There are apps that can help record your fuel use (I use road trip free version). Then decide if it’s worth it. It won’t cost you much to experiment over 3-4 tanks.
FWIW, I had a 2003 Forester and couldn’t tell the difference in consumption between the fuel types. Driving style was he biggest difference, ie did I spend time on the highway out of the ordinary, or was it really hot and I had the Ac on (I didn’t notice the difference with Ac).
There is a big recent thread on this topic with no clear conclusions. Just lots of “right” people.
Depends on your car. My 06 civic get more than 600 kms out of a tank of 98 but only 450 km out of a tank of 91 when doing only highway driving. My other car, an xtrail, makes no difference no matter what fuel I put in.
Why do people ask questions here that they can get expert advice on with a simple Google search?
https://www.racq.com.au/cars-and-driving/cars/owning-and-mai…