Well, high grade is what you SHOULD use.
A lot of people have trouble understanding what high grade gas actually is. After all, we remember TV commercials that make you think that THEIR high-test gas gives you more horsepower, or better mileage, or something. Gas is gas, it's the motor that gives you good or weak performance. But one major way to increase power is to increase the motor's compression. The tradeoff is the tendency to "pre-ignite". When the air/gas mixture is heavily compressed, it gets really hot, and it ignites before the spark plug fires. That's what sounds like marbles inside the motor. A higher-compression engine requires a higher-octane gas, as the octane is a retardant that reduces the tendency to pre-ignite.
In the case of my motor, which is a LONG story, the compression actually measures low. My guess is incorrect rings. Whatever, it burns oil like crazy. I've figured as long as the compression is low, I'll take advantage by using mid-grade gas -- and it runs fine. Oh, someday I'll have a local shop go through this motor for me.
Nothing wrong with Mustangs -- they are neat cars! On the good side, they are easy to work on,
parts are readily available and cheap, the cars are simple and practical, and they make great daily drivers. On the bad side, as old cars go they're a bit too common -- take it to a car show and park it with all the others. Thunderbird is more of a luxury car, built in the Lincoln factory with the attitude of "why use 3 moving
parts when you can use 47?", and with a smaller population base you'll find some repro
parts are up there in price. For whatever strange reason the finished car isn't worth that much -- can't figure that one out. I guess it's not a sporty muscle car, it has all the hardware but weighs twice as much. But it's certainly a nice ride, and it is definitely an attention-getter!
