Is it required to have 91octane in an 04 Acura TSX? Will it cause engine damage? Can I put regular unleaded.?

Question

Is it required to have 91octane in an 04 Acura TSX? Will it cause engine damage? Can I put regular unleaded.?

Answer 1

You purchased a vehicle with a fairly high compression motor. Your overall gas mileage will suffer because the anti-knock sensor will constantly be retarding ignition timing to prevent spark knock and pre-ignition. The power falls off and excess heat is generated in the combustion chambers. High test gas burns slower, more completely and cooler.

The continued use of low octane fuel will eventually over-heat the pistons and valves shortening the life of the motor.

Answer 2

the 2004 TSX has a fairly high compression ratio at 10.5:1, but by the same token so do V-tec equipped honda civics.  You will get more performance out of the 91 octane, but you should be fine running regular.  Make sure that this is the case by carefully reading what it says in your owner's manual and what it says on your car.  This is usually written on or near the gas cap and on the dash board.  If it says that it is recommended to use 91 then you can get away with running regular.  If it says use 91 octane or higher, or use premium unleaded fuel only, then you have to use 91 octane or higher.