Joe writing to JKat:

I have always had mixed opinions about octane boosters and actually never used them.
Portland has a Fed. mandate that we have to do better cleaning the air and as a result we have
“oxygenated fuel” which is gasohol.  Makes all cars run terrible in the name of the environment??
Anyway, the BMW just was not running right recently and has not felt up to par for some time.
That car has 10.5 – 1 compression, which I know they did for mid-range cruising economy and not for accelerating.
Anyway, I was reading that the sensor that detects the octane in the fuel, will make full use of the 10.5 compression if octane is high enough.
Unlike a distributor that has a theoretical static advance, the BMW sensors detect the real octane and from that
find the ideal.   Anyway, I tried 108 Octane Booster that a friend recommended and wow, what a difference.
The engine sounds much more fierce and performance is like adding 40 HP or so.  Someone else said that
Lucas Octane booster is very good,  but that one costs about $9.00 for a very small bottle, so i went with the 108.
At about $4.00 per tank, the 108 clearly is giving me better gas mileage and oven an entire tank of gas is paying for itself,
not to mention better acceleration.   Even my low first gear is not very noticeable with the higher octane.