Verified answer

premium is used for higher compression engines (sports cars typically) or used in engines with forced induction because higher octane gas is less prone to predetonation under high temps (the result of compression or hot air from the turbo). in sumation dont waste money on preium unless your car manual specifically says use premium.

from personal experience=I own a 06 6MT tsx , bought new 11/17/06. I do mostly highway driving but drive it conservatively. No high-revs, or racing. I have all the service done by an acura dealer. They compliment me on how well my car is maintained. The original tires lasted 74,000+miles and the replacements have almost 60,000 miles. The car still has the original brakes. This gives you an idea on how it is driven. I average 30-35MPG using regular gas. My car has almost 134,000 miles. Many of the 09 tsx had problems with the engine pinging-even when premium fuel was used. My car has no knock or pinging (knock-on-wood) If you were to drive my car and did not know I used regular gas you would never know. It runs excellent. According to the owner's manual it states-not to use gas with an octane less than 87-using 87 octane will NOT void your warranty.

Read this post on what happens when you use 87 in an engine that requires 93

http://www.ricksfreeautorepairadvice.com/repair-to...