I was about to purchase a 05 RSX-S with 64k miles from the orginal owner. He told me that he only used medium grade gas throughout the car's life. I told him premium is required, he said he didn't know. Anyways, what implications should I expect if i purchase the car that's been using 89 octane throughout the car's life for 64k miles?

Thanks

 

You live in California where you have **** for gasoline anyway. Not much of a difference between 89 vs. 91.

Just buy a can of fuel system cleaner and run it through the system, you should be fine.

 

Werd. Its not that much of a difference but uf u do buy it would use premium. I use 93

 

QFT!! Don't even trip dude. Juat do what ^he said.

 

There will be no ill effects from a life of 89 'tane, the knock sensor tells the computer to retard ignition timing to avoid damage

 

Octane rating has nothing to do with fuel cleanliness. People often put premium gas in their 87 octane rated cars because they want to "treat their car" which is dumb because if your car doesn't require premium it won't make a difference. Octane rating only has to do with resistance to knock which is why it is required for high compression and turbo vehicles. As with your Type S... You can probably feel safe that maybe the guy never stomped on it. Ha ha. The car would just calibrate the engine to run on lesser octane and have less power and such.

Some new cars even come with two difference ECU maps loaded so when it detects the car is on regular gas it detunes to one ECU map and when it detects premium it runs a different map. I think the new Hyundai Genesis sedan with the 4.6 V8 or whatever does that.

 

I wouldn't hit it till you swapped fuel completely. A buddy blew a civic engine by cheaping out to 89 octane.