DaphneLCC

So, forgive me if this has been discussed... I did do a search and didn't come up with an answer to my question....

However, a friend and I were talking about what type of fuel we put into our cars and when I told him I put in premium 91 octane gas into my TSX, he told me that because we live at higher altitudes, it's okay to put in mid-grade... I want to say it's 87 octane here. When I search through the forums, I found a lot about the ranges of octane ratings for regular, mid-grade and premium due to altitude, but nothing on this particular query. Can anyone prove his point?


I also had another question... a bit off-topic... But I've heard this weird puttering sound when I start my car. For some reason, it seems to be coming from the left side when I'm seated. I always hear it from that part of the car. Although I haven't heard it for a while... does anyone have any idea what it may be? I have a 6sp 2006 TSX if that matters~

Much thanks for any info!

niranjan162

the higher octane is to prevent knocking, i dont think altitude will have much effect on the compression ratio. Some people use mid-grade which is 89. Ive only used premium so far for the summer.

STEELTOWN

You may just want to do a "Search" on the internet, "octane versus altitude". There is a reason why places that are high above sea level sell lower octane level fuel. There are a lot of ideas on the matter and you can decide what makes sense...

Trophyhead

As a fellow Utahn, stick with premium. It is true that higher altitude requires less octane, but stick with the highest grade available here.

DaphneLCC

Hm... Maybe I'll scour the internet to find some factual backing. I just want to prove him wrong

Thanks everyone for the info, suggestions, comments, etc...

calbear2k1

You still should put premium in your car. Your local high altitude gas station sells a premium with an octane rating 1-2 points lower that at sea level. So they have done the adjustment for you.