87 octane vs. Premier gas

[mez]

Just got my son an used 2002 TL. It "requires" premier gas (91 octane). I tried both 87 and 93 octane and found no differences. The car seems to run just as well on the lower grade. Will using the 87 octane cause any harm? I read a article in the local newspaper stating that the computer will adjust for the lower grade gas. Your thoughts.

 

[uconn1150]

Run each for 5 successive tanks and check your mpg. The computer will adjust for lower octane which "usually" results in less hp and mpg. Sometimes it's worth the few extra mpg (2-3). Each car/engine/knock threshold is different. My B16 likes the good stuff and gives me 2 mpg more. Remember as gas goes up past $3, premium isn't as bad percentagewise (still 20 cents more).

 

[Panzerman]

My wifes car requests Premium gas and Ill sneak some 89 in it every now and then but when I put the 87 in it, its a dog and is loud, even with the knock sensors, if it says use premium gas, I would. I think this is more important than even using a 10w30 when it reccomendes a 5w20, I also think it would be more damaging. Its just the price you pay for driving a hi performance or luxery car.

 

[Win]

If the car requires premium gas, pony up and put premium gas in it.

Every car I own that specs premium fuel gets significantly lower fuel economy when run on a lower grade. It's a false economy to put cheap gas in a car that was not made for cheap gas.

 

[mechtech2]

Win is right on.
No Mfr will ever recommend premium unless the car really could use it.
You stand to gain a lot percentage wise, but the cost increase is not as great, percentage wise.

 

[txtruck]

use the best octane to ward off detonation. higher compression and advanced timing often requires higher octane. in the winter you might be able to get by with 87 a nd depending on how hot it gets mayb 89 in the summer. if your not getting any knock or loss of performance with 87, 93 isnt gona help. the cp WILL learn that its got less octane to work with and pull timing accordingly once it starts reading detonation. higher octane does NOTHING if your motor is already running at advanced timing and no detonation