amiro

I know the Audi 1.8T manual recommends a minimum of 91 octane, but i was wondering, for our other car (2005 Mazda3 Sport - nice car, BTW) its manual says minimum 87 octane. Would you just put 87 in there, or maybe 89? It's not modded, and not driven too aggressively by the wifey!

paul_858

hell i'd run as low as the engine could without risking pre-detonation.

RKA

If it says 87, the car won't advance the timing to take advantage of anything higher than 87. On older cars (that aren't running well), sometimes they'll run a little better on a higher octance gas, but generally it's not necessary, and usually it's a waste of money.

Ritz

If you run 87 or 89 in it, the timing will just get retarded when knock is detected. If you're driving in granny mode you probably wouldn't notice the loss of power.

Cheers,

RKA

When they use the word minimum, they are trying to say "don't use anything lower", they are not suggesting "higher is better".

sdaman88

go with 87. i was even told by an audi dealer that 87 could be used in the audi and i have seen no problems...accually runs more smooth

RKA

The ECU will compensate for the bonehead owner by retarding timing. End result, lower power, less MPG (possibly enough to outweight savings on fuel prices).

iammatt

if there's a $.20 differece a gallon in 87 - 91
and you fill up twice a month (15 gallons)
and you drive the car 12 months

you'll save $36 / year.

don't be cheap, get 91.

oh, but you are asking for the mazda. so forget it and take your wifey out to a $36 dinner - on me!

amiro

Thanks everyone. The compression on that engine's 9.7, higher than the 1.8T's!

RKA

You hoping to get lucky with his wife?