I use regular almost all the time if I get a knock I cam use a higher grade at 1/2 tank mark, it did happen once but with about 25,ooo on the clock once is not bad.

 

Use fresh premium when available, carry Rocket Fuel just in case, but as others have said, the occasional tank of regular won't hurt anything.

 

Haven't burned anything but the cheapest gas available from day one. 17K and it runs great.

 

http://www.debrix.com/items/item.aspx?itemid=1860312

 

I just use regular...modern day ECU's can compensate by retarding the timing..

u get better gas mileage on the premium though...

 

Never had any issues running the cheap stuff if that's all they got.

 

I use 89 in my SG all the time. It never knocks or gives me any other grief.

 

Higher compression engines (than stock) will require higher octane or they will knock.

 

Im always a little skeptical when an add claims something technical such as:

"increases motor octane"

wtf?

 

Maybe you need to look at this:

Measurement methods
The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane.

There is another type of octane rating, called Motor Octane Number (MON) or the aviation lean octane rating, which is a better measure of how the fuel behaves when under load. MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, a higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON. Normally fuel specifications require both a minimum RON and a minimum MON.

In most countries (including all of Europe and Australia) the "headline" octane rating, shown on the pump, is the RON, but in the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, the octane shown in the United States is 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, is 91-92 in Europe. However most European pumps deliver 95 (RON) as "regular", equivalent to 90-91 US (R+M)/2, and some even deliver 98 (RON) or 100 (RON).[citation needed]

It is possible for a fuel to have a RON greater than 100, because iso-octane is not the most knock-resistant substance available. Racing fuels, AvGas, LPG, and alcohol fuels such as methanol or ethanol can have octane ratings of 110 or significantly higher - ethanol's RON is 129 (MON 102, AKI 116). Typical "octane booster" gasoline additives include tetra-ethyl lead, MTBE and toluene. Tetra-ethyl lead (the additive used in leaded gasoline) is easily decomposed to its component radicals, which react with the radicals from the fuel and oxygen that start the combustion, thereby delaying ignition, leading to an increased octane number.