2003 CTS - 87, 89 or 91 octane - What is really needed?
 

Will a 2003 CTS run just fine on 87 octane? or 89 octane? What are your experiences?

RE: 2003 CTS - 87, 89 or 91 octane - What is really needed?
 

what engine?

RE: 2003 CTS - 87, 89 or 91 octane - What is really needed?
 

From what I've read through automotive magazines, if your car is designed to run on one type of fuel, it won't damage the engine to run the other types because the computer will adjust accordingly. The only thing that it may change (besides money in your wallet) is fuel mileage. The car most likely get the best fuel mileage according to what the manufacturer specifies. Going to super unleaded from a car which is supposed to use regular unleaded may reduce it's gas mileage.

RE: 2003 CTS - 87, 89 or 91 octane - What is really needed?
 

If you run a lower octane and notice a rattling noise under load or an unacceptable loss in power than switch to the next higher octane. The hotter the day the more likely these are to occur.
Your engine computer has a huge saftey feature built in to keep your engine from being damaged by poor fuel or low octane.
This may come as a loss of power and/or mileage when needed.

RE: 2003 CTS - 87, 89 or 91 octane - What is really needed?
 

the 3.2L V6 MPI DOHC

RE: 2003 CTS - 87, 89 or 91 octane - What is really needed?
 

thanks. don't want to hurt the engine but don't want to waste money for just driving around town either. I'll try the 87 then the 89, if the 87 gives me trouble.

RE: 2003 CTS - 87, 89 or 91 octane - What is really needed?
 

nice looking vehicle. Thanks.

RE: 2003 CTS - 87, 89 or 91 octane - What is really needed?
 

Your vehical can run on 87 if you not in high altitudes if your in colorodo then you might run 93 but if your in florida then 87 is fine if it runs rough get the fuel system cleand

RE: 2003 CTS - 87, 89 or 91 octane - What is really needed?
 

I would recommend 89 just because it burns a lot better then 87 does. The key to different octanes is the degree of heat it takes to detonate the fuel. If you run 87 then the temperature need to be high or the spark made by the spark plug has to be greater to compensate for the type of fuel in the chamber. 89 will take a lot less effort to detonate the fuel because of the quality of the fuel. 87 octane is thicker, and 91 is the lightest of the two fuels. I hope I was of some help to you.

Thank You,