For a daily driver that runs ok on 87, filled up with 89- runs better, more responsive, overall nicer drive. But is it a wash on $ differential vs economy? My impression- it is NOT.
Last edited:
Anybody run the octane numbers?
- Thread starter dfarr67
- Start date
Sounds like you have made a decision to run 89 Octane?
I bought a Yamaha FZ1 years ago and the owner swore it ran better on 89 octane. I didn't listen to him and for months I ran 91 octane. One day I thought let me try 89 and sure enough it was more responsive. No idea why.
I bought a Yamaha FZ1 years ago and the owner swore it ran better on 89 octane. I didn't listen to him and for months I ran 91 octane. One day I thought let me try 89 and sure enough it was more responsive. No idea why.
We get 95RON E10 and 98RON E5. I can't notice any differenve between the two, at least not during winter. Got a road trip planned in May, might try 98 again.
The reality is that E10 isn't likely to contain 10% ethanol, as in europe the gasoline density must stay in spec, and you'd need heavy fractions of fuel to do that. 2-5% seems like the norm. Not enough to notice a mileage drop.
The reality is that E10 isn't likely to contain 10% ethanol, as in europe the gasoline density must stay in spec, and you'd need heavy fractions of fuel to do that. 2-5% seems like the norm. Not enough to notice a mileage drop.
We have winter fuel here, not aware of any other EXX grade. Other than an engine designed for the higher octanes- I don't think it's worth the extra $$. Company vehicle, just giving it a 'treat' and seeing how fast the ecu compensates.
I believe it depends on your engine. Most N/A current Subarus like mine are fairly high compression (around 9.5:1 to 10.3:1). I see a small increase (1-3 mpg) in mileage with higher octane fuel. This is something I've monitored over the 15 years I've had this car and is apparent across weather and driving conditions for me.
So all in- does it pay for the upgrade?
This is an abused loaner as my regular chev's transmission failed. 2012 Rav.
Some vehicles have the ability to adjust spark tables in response to knock. (or lack thereof) This will give you a little more power and slightly better fuel economy, but it's a long shot from breaking even on cost. You realistically might notice a +2-4% difference which won't offset the ~20% increase in fuel cost. Some people may consider the cost worth it for the little extra power, but I don't.
The mid-grade 89 fuel is a blend of regular and premium pumped at the same time.
This is a test from a Shell station a few years ago that shows between 9-10% ethanol in both regular 87 and premium (V-power) 91. Granted, this is in the US. Just 10% won't move the SpG very much.
The mid-grade 89 fuel is a blend of regular and premium pumped at the same time.
This is a test from a Shell station a few years ago that shows between 9-10% ethanol in both regular 87 and premium (V-power) 91. Granted, this is in the US. Just 10% won't move the SpG very much.
I know of two long term user "studies" if you will, where they controlled as much as they could. One was a R51 Nissan Pathfinder, which has the same mechanical VQ40 as my two Nissan's except it has a slightly different control setup and calls for 89 - we all assumed to get through cafe because they also run fine on 87. The other was the current generation Rav4, which I think was a AWD - ice model for sure.
They both documented improved mileage - but not enough to justify the additional cost. The cost around here is like 10% more, and they were seeing 3-4% mileage improvements - across multiple tanks.
They both documented improved mileage - but not enough to justify the additional cost. The cost around here is like 10% more, and they were seeing 3-4% mileage improvements - across multiple tanks.
I live in a rural area now where with the base cost of regular is so expensive that I feel the premium fuels just hang around in the ground and go stale, some stations have discontinued the premium option altogether. I have a 89 K1500 with a 385 (9.6:1 alum heads) and a 2015 Accord (DI) which years ago were retuned on 91 octane before prices got out of hand, I re-altered the timing tables on the Honda back to stock but should really get a fresh retune on 87 as I think the knock system works well enough that I might not know how bad the current tune is knock wise. The truck does not sip fuel and I occasionally work it with towing- got into some BAD gas and it let me know about it- this too needs to be retuned for 87 but does have the capability to hold several different tunes. Previously I was on the theory that the extra cost somehow paid for itself if the vehicle was properly tuned for it. This statement does recognize engines where they are simply designed for higher octane.
Our Carnival has 12.3:1 compression, and dual-injection. It runs a lot better on 93. It’ll run on 87, and the mpg is fine. But 93 gives it so much more power. You don’t have to be ragging on it to notice either. Like most modern cars this thing loves to be in 8th gear by like 10mph, so you're always trying to move forward at low rpm. With 87 it feels like it’s being held back. With 93, it just drives much better. Haven’t run it long-term on 93 to tell any mpg improvements, but the driving experience alone might be worth it.
FWIW, the manual states that 87 or higher is fine, but actually recommends 91 or higher in the maintenance section.
FWIW, the manual states that 87 or higher is fine, but actually recommends 91 or higher in the maintenance section.
This is basically what I have read on multiple forums. Some cars get a small % increase in MPG running premium, but the cost difference is much greater. I haven't heard of much of an increase using mid-grade over regular gas.
I ran mid-grade in my motorcycle that called for premium and it ran fine for 40K miles. It had sensors and would adjust for low or high octane fuel. I could get more performance with premium, but I didn't miss that extra few horsepower in my normal riding. I didn't notice any increase of MPG over a normal tank-to-tank variation.
Why don't you do it and get back to us? Probably different for every car.
My Odyssey runs noticably better on 93.
My 2013 Ram 1500 5.7 manual recommends 89, but says 87 is okay. I do notice a slight drop in mileage using 87 or (E15) 88, especially when pushed card. My dad’s 85 Chevy Caprice winter beater ran noticeably better on 89 vs 87.
Patman
Staff member
Just for fun I tried running a couple of tanks of Shell 93 in my Civic last year to see if I could notice any difference in how the engine responds or if the fuel economy changed. No difference whatsoever that I could see, so I went back to using Costco 87 again. I feel like there are very few cases where a car that calls for 87 will actually show any benefit from running premium fuel. The only time I would consider it would be if I had a turbocharged vehicle that calls for 87 (such as a new Mazda3 Turbo that can use 87 but will make more torque if you use premium)
Locally, 91 or 93 octane is usually about 20-25% more than 87. So I don't think any car that actually runs on 87 without damage, is going to see a mileage increase of that size. So I never bother normally, only when I've been taking a car to autocross or the track and might be using WO at lower rpms. I can't say I've ever noticed a bit more power at low rpm, but I do notice a full tank vs a 1/4 tank.
In the US where the prices are closer, I think while towing, many vehicles would break even on the price for putting in 89 or 91 octane. I've read that in a few forums for the odd SUV that recommends 89/91. In normal driving 87 is fine, but when towing, the engine has to pull so much timing that it pays to run higher octane.
Also perhaps something with a CVT, where the rpm and gear ratio can be adjusted for maximum efficiency given the amount of power needed, if you do a lot of highway driving or have a light foot around town, maybe 5% is attainable?
In the US where the prices are closer, I think while towing, many vehicles would break even on the price for putting in 89 or 91 octane. I've read that in a few forums for the odd SUV that recommends 89/91. In normal driving 87 is fine, but when towing, the engine has to pull so much timing that it pays to run higher octane.
Also perhaps something with a CVT, where the rpm and gear ratio can be adjusted for maximum efficiency given the amount of power needed, if you do a lot of highway driving or have a light foot around town, maybe 5% is attainable?
Last edited:
I also can't tell the difference driving my Civic. Best fuel in my area is 91, though. No 93 at any stations I frequent.
87 pings in my F-150 5.0 and the E15 88 octane does a little better, but it runs best on premium 91. I rarely run it though because it is $1 more per gallon at my station which amounts to a $30+ increase in the cost of a fill. Some stations are a little cheaper for premium that includes ethanol like Sams Club