Optitron

What would happen if I downgraded to 89 grade gas vice 92 grade?

Meowloud

Please search. I know I've seen this discussion several times already.

MMGDC

You would save approximately 7 cents per gallon.

BlueGrimRX8

I am currently doing a little test to see, I did 10 fill ups with Mid Grade 89 and have now gone down to 87, I want to see if the MPG changes as well as performance, so far only one fill up with 87 so we will see.....

srm858

This has been talked about before, but no definitive answers. I have been using 87 for several tanks and I can't tell any difference in performance or mileage. The manual says it's OK, so why not? The last tank I used premium and mileage seems the same and performance is equivilent.

willhave8

I have a small sampling (5 or so tanks with each) but I cannot see any difference in MPG betwen 87 or 93 octane. (15 to 18 mpg) The most significant variable to my mileage and it has been reported very well here already, is % driving on the highway (defined as time at 55+ mph). I am now staying with 87 Octane and call me **** but I only buy Shell gas only for consistency.

Navybeardbb

7 cent saving from 92 Octane to 87...what state is this in. Cali it's about a twenty cent difference from 91-87. But a dollar doesn't really matter to me.

Other_Dave

You would save about $1 per fillup (not much) and your engine computer would change the timing and mixture to avoid pingng. The new timing and mixture should reduce the power you have available, but perhaps not noticably.
--Dave.

mikeb

you should change your AVATAR:D

MMGDC

He said 92 to 89...

In NJ, the difference between 93 and 89 is usually around 7-10 cents. 87 and 93 is typically closer to 20 cents though.

To give a more serious answer, I use 87 3 out of every 4 fill ups, 93 in the 4th. I've noticed absolutely no difference in mileage, although the acceleration "feels" a bit more responsive with the 93 octane. Could be my imagination though.

Optitron

The reason I ask is because I drive 120 miles a day and I'm looking at every chance to save money. I mostly drive about 65 on a rural two-lane highway. I notice a considerable difference when I pass people that drive slower than me. I wanted to know if the engine will run correctly through prolonged stress with a lower grade gas.

Texas 8

Same here....

weiweiwei

what does the manual say to use?

MazdaManiac

iTrader: (3)

Tired of editorializing on this simple bit.
Here's the page. Decide for yourself.

Optitron

Sorry I was too busy to sift through the other threads.