Honda Car Forum

increased MPG

Octane is added to gas to increase the flashpoint to prevent the gas from pre-igniting in a high compression engine. That's all it does. 93 octane gas has the exact same energy output as 87. It just ignites at a higher temp. If you use 87 in this car, it will cause all kinds of misfires because it will ignite before it's supposed to.So really, you don't get increased mileage with 93. It's that you get worse mileage with 87 because it's pre-igniting and causing misfires.RickI'm a retired ASE Master/L-1 Technician. I still keep current with the latest automotive technology. Visit my blog for cool articles and TSB's: http://free-auto-repair-advice.blogspot.com

If my owners manual recommends high octane thats what it gets. I'm the one who bought the car and knew what I was getting into. I'm not willing to risk messing up my engine to save $3.60 on a tank of gas (18 gallons at 20 cents more per gal). I've heard all kinds of stories about how the gas all comes from the same tank and the store owners don't put the octane additive in the high octane supply, etc, etc. It's still not a risk I'm willing to take. I bought the expensive car so I have to put in the expensive gas. If I can't afford it or don't want to afford it I need to buy an Accord.

well it recommends premium because of the higher compression engine. Higher compression leads to higher cylinder temperatures. If you use a lower octane then the gasoline might pre-ignite (ignition before spark plug sparks) if this happens damage occurs, but your engine has a knock sensor which will detect this and retard timing. The retarded timing will cause worse performance and less gas mileage. So basically follow the owners manual, they know what they speak off.

So what's your question?If you own a car that requires Super, then that's what you need to use in it. The TL gets pretty good gas mileage on a run considering the performance of the car.

It's likely you'll get poorer milage from lower octane fuel, offsetting in part the price difference between the fuel grades. The problem is that 87 octane will prevent your engine from running up to it's rated output. The TL (Gen 3) employs an 11:1 compression ration that will cause detonation (ping, knock) with lower octane gas. In order to prevent potential serious engine damage, Honda uses a knock sensor that retards the ignition when lower octane fuel is used. And what they don't tell you is that continuous use of lower octane gas in an engine made for premium gas will likely cause carbon buildup in the cylinders & on the pistons...with a contiumous diet of 87 gas, the car's going to run sluggish. Then carbon buildup creates 'hot spots' on the pistons that tend to lead to even more detonation problems, meaning the knock sensor will retard the ignition even more to prevent this.It's best to stick with premium fuel with the TL...a tank of 87 here & there in emergencies shouldn't be a problem.