He had 94 octane here in Ohio for a while (at Sunoco) but they got rid of it

 

Until just the other week, all stations in this town had 87, 89, and 91 octane. A new Phillips 66 station began offering 94 octane, and now several other stations are following suit. This makes for a happy Rover.

 

In a nutshell, a higher octane rated gasoline is less volatile, meaning it is less likely to spontaneously combust under temperature and pressure relative to a lower octane rated gasoline. The octane required in a vehicle is determined by it's engine's compression. Using a lower octane fuel in one engineered for higher octane will potentially result in pre-detonation, a.k.a pinging. This means the more volatile lower octane fuel is attempting to combust and expand spontaneously before the piston has reached the top of it's stroke, so the engine is fighting the force of combustion, and attempting to compress an ignited and expanding gas. I can't emphasize enough how detrimental this is to an engine.

This "pinging" happens more audibly under load, but will happen at inaudible levels at cruising and even idling speeds. The tendency to ping increases as engines age because carbon deposits that collect in the cylinder head can retain heat and promote detonation prematurely as well much like a glow plug in a diesel. All the more reason to use a high octance fuel in a older vehicle, since pre-detonation is a primary cause of premature engine failure. Also note that the octane rating is an average of two different ways of measuring octane, research and motor octane. Two fuels can have the same average octane rating, but each can have a different motor and research octane. This explains why two fuels with the same octane rating can perform differently in your vehicle. So always listen for pinging in your vehicle especially under load and get off the accelerator immediately if you hear it, then fuel up with the highest octane fuel available as soon as possible, and drive gently in the meantime. Also, buy your fuel from a trusted supplier on a regular basis.

BTW, the petroleum industry has created it's own quality system called Top Tier several years ago. It was in response to complaints from manufacturers that carbon deposits on cylinder heads were directly attributable to the quality of the fuel and it's additive package. Top Tier fuels have better detergent packages to prevent the formation of carbon deposits. For this reason, and to prevent pre-detonation, I try to use a "Top Tier" rated fuels whenever possible. Here's more information and the list of current vendors:

www.toptiergas.com

 

I was just trying to keep the math simple.
Gas here today on my way home was down to $2.69 per gal for regular.

Now if you really want to save money on fuel get the Shell Saver Card, you will save $0.05 per gallon on fuel.

http://www.shell.us/home/content/usa...aver_card.html

I have one for over a year now and I love it.

 

Thanks everyone. It was an innocent question from a soon to be Disco Series 1 owner.

 

Make sure you look it over good or your will be disappointed with someone else's problem child.

 

I am use to seeing the 10 cent jumps for regular to mid-grade to premium for years, but in my local area in SW Va all the name brand stations are now doing a 15-20 cent jump on premium often times from the mid-grade price. We are seeing 2.42 for regular and best name brand premium I can find is $2.69 this weekend.

 

My preferred station started doing a 12 cent spread from mid grade to premium, if it was not for the Saver Card I would be buying my gas elsewhere.