Quote:
Originally Posted by AntoineWG
It's not so much the grade/octane rating of the gas as the quality of the gas. Buying cheap gas now means you'll pay for it later with a gunky engine. Spending the extra buck or two on each tank on quality gas (I use BP or Shell) will keep your engine cleaner and save on maintenance in the long run. A 5 cent difference between brands for the same grade seems like a lot until you realize that on 20 gallons, the difference is only $1.
The octane rating has to do with how stable the gas is under compression, which means little in an Atkinson cycle engine. That's why you can buy 108 octane racing fuel, which has a higher ethanol content.
Back when I bought my Blazer, I had nothing but problems after about 6 months. I was using cheap (Jewel and Meijer) gas and my brother was using cheap gas when he had it. I got the engine tuned up and cleaned out, and even cleaned a bunch of sludge out of the tank when I replaced the fuel pump. A year later when I had to replace the fuel pump again (long story short, don't buy the cheapest pump even if it has a lifetime warranty) and the tank was spotless. After 2 years of using quality gas, the engine was running perfectly when I sold it, and getting slightly better gas mileage than when I bought it.
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I agree that quality is the key to preventing most fuel problems. Of course, one should always use the octane fuel specified by the owner. Going to a higher octane rating wastes money and provides no benefit. With the altitude here regular is rated at 85 octane but my HAH is speced for 87, so I am usually stuck with buying mid-grade.
Because most areas are like where I live here in Casper in that all the gas comes from the same refinery, (Sinclair is this case), differences in quality of fuel are related to the local station storage. Any additives unique to a brand, EXXON, Shell etc., are added just prior to a delivery. The basic fuel is the same. Some stations here, notably CONOCO, sell a 10% ethanol blend. I am not sure where that comes from but I would bet it is also a custom blend using the local product. I don't purchase ethanol in as it is usually the same price but has less energy content and I can notice a drop in MPG.
Since one can't examine the insides of the storage tank at the station, one option is to buy gas at stations that do the most volume of sales. The turnover in the storage tanks is probably high and therefore the potential for accumulation of sludge is low. I my case the usual fill is done at an EXXON station because it is always the lowest price or a tie for low, has non-ethanol fuel, and seems to do a large volume of business.