I was wondering what grade of gas everyone was putting in their TCH. I know that some cars really need and/or can make good use of premium, and others don't.

I've been putting in basic because of the price, but I'm wondering if going up to the middle grade will make any difference in performance and/or mileage.

What's everyone's thoughts on this?

Nope going up on octane will not make a difference with the TCH 's engine. Our engines were not designed for use with the higher octane.

OK, cool. Thanks!

Wes Tested, Earth Approved

I was just reading the the manuel in my " office" and the book say's 87 octane.
Well here in California 87 is midgrade. It goes 85-87-92 octane..

Wierd that grades are so different. In WV it's 87, 89 and 92 or 93 (varies)

Hmm, I've only seen "85" for regular when filling up at higher elevations, typically over 4 or 5,000 ft. Here in San Diego 87 is regular.

If you are going to drive most of the tank at the higher elevation, then 85 octane is just fine.

Putting anything higher than 87 octane in the TCH is a waste of money. There is no reason to use higher octane unless that car requires it (the manual will say so, and the fuel gauge/fuel cap will say premium fuel is required).

There was a similar discussion on the Prius boards a while back. One knowledgeable person (a chemist?) made the point that higher octane gas actually has less energy content (per gallon).

I think that makes sense.

The higher the octane rating, the more difficult it is to ignite the fuel. This is needed for higher compression engines, since compressing the fuel/air mixture causes it to heat up, and this heating can (in some instances) cause the fuel to ignite prematurely. This is often called pre-ignition or detonation. It usually sounds like a "pinging" noise (or rattling pebbles).

This pre-ignition is very damaging to the engine, and the higher octane gas is needed to prevent it from happening.