I try and put Optimax in as much as possible, but it depends on where you stop for petrol.

 

I'm quite lucky in that I have about 6 Shell garages within a few miles of where I live, but when I'm out on one of my drives finding one can be quite difficult. I actually used the station locator on the Shell website with my mobile phone at the weekend , but as I didn't know the area I couldn't find it from the address, I was about to run out so used

 

There is no doubt about it, we do get ripped off in the UK on fuel.

 

So Honda recommends 91 octane? I really don't mind paying $1.00 extra every fillup for 93 octane if it is beneficial to the engine and will reduce the risk of detonation.

 

we don't even get 91 here. we have 87, 89 and then 93.

 

[QUOTE]Originally posted by QIKSILVR

 

This octane business is difficult to explain, as your octane requirements depend on altitude. Owners manual says 91. Where I live, it is 550' above sea level, and premium gas is 91 octane, and I use it. In the Colorado Rocky Mountains where elevation is 5000' to 14000' above sea level, the air is thinner so we effectively do not have our full compression ratio. This reduces the detonation issue, and the highest octane available there is 89. I have been advised that use of 89 octane is fine at these altitudes. Now if we go to a coastal city where elevation is near 0' above sea level, air is thicker, effectively increasing our compression ratio. In such locations, premium is often 93 octane. As there my compression would be higher on the coast than at my home, I would probably consider using the 93 octane there.

Thanks,
Richard

 

I find the past 2 posts very informative. What do you think using a mixture of 95 octane increases the HP, if any?

 

putting anything less than premium might save a few bucks @ the pump, but the damage that you're doing to your engine makes it more expensive in the long run... be good to your baby and do atleast 91!!!!

EDIT: thanks for the octane/s2k info! good to know!

 

I've used 98 and 100 on my N/A S and haven't noticed any real difference here in California, but when I put it in my wife