When I bought my S40 new this year, the dealer had filled the tank with 93 Octane, and that is all I have ever put in it.  Runs good with plenty of response.

Kropatchek,

In the US (and Canada, I think) the octane reating posted on the pump is the average of the Research Octane Number and the Motor Octane Number, (R+M)/2.  So our 93 octane is probably about the same as the European 98 octane.

I typically use the higher octane grade.  The price difference is not significant.  This also avoids the 10% ethanol mixture that is sometimes found in the lower grades around here.

Steve

Been trying everything from 87 to 93 octane and can't tell the difference in cooler weather. During the summer 93 octane seems to reduce engine ping so I fill up with it every second tankfull. I really want to find a Cam-2 dealer and get a couple gallons of the 104 octane, hee hee, I bet the thumper would break the ton mark with a tank full of that .

This is a complicated topic.  Someone already pointed out that SOME high-octane fuels have different mixtures and detergent packages, so what are we talking about here?

87 octane is PLENTY for an engine below 9:1 compression, especially with only a 3.7 inch stroke.

As already noted, ethanol is not good for rubber and aluminum.

Good detergent packages will help with carbon deposits.

How do I solve that?  I don't trust the oil companies since they're just trying to make a buck.  I use 87 octane, try to avoid ethanol whenever possible, and put Amsoil gas detergent additive in every tank-full.  I'm getting 60 mpg.

Using higher octane than required is not helpful.  Octane DOES NOT increase thermal energy potential.  It is simply a measure of how quickly fuel burns.  Higher octane fuels burn more slowly.  Low compression engines produce slower burning.  This combination (high octane and low compression) causes fuel to burn at a time that does not contribute to the power stroke or outside the combustion chamber.  You want the gas to burn at the rate the engine was designed for which is also a function of ignition timing and several other factors.  An extremely hot engine can benefit from higher octane, since heat will increase combustion speed somewhat, but a condition like that should be remedied some other way...

For any other "motor-heads" out there, this is really just "engines 101."

Spend money on what you need for the Savage, Detergent, not Octane.

Just my 2 cents.  (Pun intended.)

I do agree that running even a 93 octane gas won't affect perfomance noticably and just costs more but it has been my experiance that using a racing fuel such as Cam-2 even in a low compression engine really makes a difference. That doesn't mean that I advocate using racing fuel for everyday riding, now that would be a real waste of cash.

I agree with most of what has been said before, 87 is okay , 93 is okay sometime for cleaning properties. As far as 104 making your savage perform better it has been my experience that that is strickly psychological. "More octaine, more money , must be better" You should read the post before mine that explains how fuel works. And if all you can find is cam-2 racing fuel you might as well run recycled french fry oil, b/c as far as racing fuel goes it is the bottom of the barrell.

I've been known to steal Jr.'s lawn mower gas if I think he won't catch me. The only station close to me is a wreck looking for a place to happen, the traffic is wild & there have been three fatalities in cages there over the last two years.  I usually use regular, just because.