yesterday i saw 89 88 89 91 and 93 all at the same gas station!
Why does 89 exist?
- Thread starter Dominic
- Start date
- Status
So are you saying that the oil companies are making a profit???
JHZR2
Staff member
My saab is specced to use 90 octane. My BMW to use 91.
The saab can use 87 for all it cares, itll just retard spark. The BMW will ping with 89.
Most stations around sell 87 89 and 93. The sunoco dropped their ultra 94, and instead now sells 87 87 91 and 93. Perfect.
I use 89 in the saab because while not perfectly matched for its optimum power output, 89 is the minimum octane, and 91 Id be paying for one extra point that I cant really use.
In the BMW, Ive tested extensively and get no pinging with 91 (the chip's spec), so why buy 93 if I can save 5c/gallon?
I have no issues buying the higher octane fuels, and do sometimes, but with more optimized octanes available, why?
Buying excess octane is not a good thing, it is one area where (unless you dont have a knock sensor or your vehicle cant change timing) having an extra buffer is not a worthy investment, IMO.
JMH
The saab can use 87 for all it cares, itll just retard spark. The BMW will ping with 89.
Most stations around sell 87 89 and 93. The sunoco dropped their ultra 94, and instead now sells 87 87 91 and 93. Perfect.
I use 89 in the saab because while not perfectly matched for its optimum power output, 89 is the minimum octane, and 91 Id be paying for one extra point that I cant really use.
In the BMW, Ive tested extensively and get no pinging with 91 (the chip's spec), so why buy 93 if I can save 5c/gallon?
I have no issues buying the higher octane fuels, and do sometimes, but with more optimized octanes available, why?
Buying excess octane is not a good thing, it is one area where (unless you dont have a knock sensor or your vehicle cant change timing) having an extra buffer is not a worthy investment, IMO.
JMH
My Mazda KLDE 2.5l V6 calls for 91 Octane... I've tried 87 and did something like 500-550km instead of the +-600 i get on tankful of Irving Premium witch has 92 Octane BTW! And since i adjusted my base timing from 10° to 13° BTDC, it increased to 650km... amazing!!
The reason you got less mileage is one way of deterring engine detonation is by richening the mixture (using more fuel). So when you run cheaper 89 in a car that calls for 91 (which is PREMIUM), the car will back off the timing some or will richen the mixture or both to combat detonation. Typically this can be seen in the Longterm fuel trims of the engine management unit if you look at the data coming out of it.
- Status
Similar threads
