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Demon Spawn
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Discussion Starter #1 (Edited)
i was wondering if anyone is running higher than the recommended octane in the 04-09 2.3L mazda 3 motors? i am looking for feedback on this as i seem to find something odd. when i put 93 in on accident last fill up, it seems to be a bit more responsive and seems to be getting better mpg.i have turned more miles on a 1/4 tank than i normally do by about 8-15 miles i put 87 in when i first got it and it was only getting 22ish average but then i was putting 89 in for 2 tanks with what appeared to be better mpg(25-30ish), then back to 87 to see last tank and only got 19, now i am accidentally running 93 and it seems to be doing better than 87( i am 23 miles over what it was after using 1/4 tank on 87)

anyone else notice this?

i am wondering if the variable valve timing is the reason for this. i live in texas and it is very hot right now so im wondering if that is also doing it. this car does have almost a 10:1 compression ration and when a car has a 10.1:1 or up premium is recommended or required in most of the time so i am wondering if thats why this motor is seeming to do better on higher octane. no other car i have ever had has ever appeared to benefit from premium when not recommended this car seems to be though.
 

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If you are not precisely metering the fuel you put into the car, there is no way to make any valid comparisons. I filled up about 2 weeks ago and got almost 100 mi. on the 1st 1/4 tank. I just recently filled up again and got only 67 miles on that 1st quarter tank. And this is most likely because the 1st fill was much more, errr, full than the 2nd.

I say this because on the 1st fill the pump shut off when it thought it was full. However I was able to put almost 2 more gallons in before it was truly full, hence the difference between the two tankfuls. I *seriously* doubt that 93 octane would produce any better mileage figures, it simply costs a lot more money. Be smart and stick with 87 octane as long as your engine does not ping on it....

-CD-
 

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Demon Spawn
Joined
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758 Posts
Discussion Starter #3 (Edited)
If you are not precisely metering the fuel you put into the car, there is no way to make any valid comparisons. I filled up about 2 weeks ago and got almost 100 mi. on the 1st 1/4 tank. I just recently filled up again and got only 67 miles on that 1st quarter tank. And this is most likely because the 1st fill was much more, errr, full than the 2nd.

I say this because on the 1st fill the pump shut off when it thought it was full. However I was able to put almost 2 more gallons in before it was truly full, hence the difference between the two tankfuls. I *seriously* doubt that 93 octane would produce any better mileage figures, it simply costs a lot more money. Be smart and stick with 87 octane as long as your engine does not ping on it....

-CD-
thats why i asked this question as i tried it in other cars and 93 actually got me worse mpg and performance in my protege 5. however my 3 is really really good at stopping the pump when its very very full, i can never add more than another quarter gallon before it starts to overflow and spill all over the place, so i just let it tell me when i am full and thats all i put in. When i first got it, i was getting 22ish mpg the first 3 tanks (all in 1.5 weeks as i was driving alot that week, and about 70% freeway in 5th at 67ish mph) on 87. So i decided to put 89 in and it that next tank it instantly went to 26 and the next one 30 without changing my driving habits. Then 26-28ish until i put 87 last week and only got 18 without me noticing if i changed my driving habits, other than 1 extra day off work, so a few more short trips to the store. i went to another gas station friday and filled it up and the pumps had the octane buttons in a weird configuration (which i noticed 93 was middle after i started pumping, i meant to hit 89) its now got 100 miles out of a 1/4 tank for the first time since i bought it

i know normally buying higher octane than the manufacturer recommends does not get you anything but a more expensive fill up. i did also find a great way to seafoam through the vacuum on the 2.3L motor right after i filled up with the 93 however it produced no smoke so i figured the car did not need it as it must have still been clean inside (74k miles) but i doubt this would make me get 3mpg like that, even if the car had smoked a little. it seemed to gain me about .5-.75ish mpg with the protege 5. i assume thats what it would do with this car, at most.
 
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