True story. I had a BMW in the 80s that needed mid grade gas. I couldn't buy it most places so I had to buy premium. I bought it religiously, but didn't pay attention to brand. 3 years later I had deposits on the valves and the car idled badly and had severe hesitation. $800 later the engine purred and I started using Chevron or Shell gasoline. That's also when I found out about the BMW valve deposit test.

 

I always use Top Tier gas -- premium for cars that require it and regular for the cars that are fine with that. Nothing more, nothing less. Top Tier is more about the detergent levels regardless of octane -- http://www.toptiergas.com/index.html

Many local stations near me are Top Tier, including Costco and QuickTrip which is usually the lowest price when I check on Gas Buddy app.

I also won't stop at a station that has the tanker in the middle of a re-fuel. Could be urban legend, but I don't want the chance of any foreign matter swooshing around their tank coming in to mine -- would rather it drop to bottom of their tank first like sediment should.

 

I always use Top Tier premium in my Stingray.

Same goes for my wife's Range Rover, and our Harley's.

They all call for 91 or better in the owners manual.

Seems to me, if you can't afford premium, then the car might be out of your budget.

 

Note to O.P.

 

Spend 60 large on the car and then save .10 a gallon on gas? That just doesn't make sense.

 

I bought a used 97 Transam with like 20k miles on it and when the dealer had to fix a head problem with car the mechanic bitched me out for using regular gasoline (LT1) engine and the piston heads were all browned out and looked bad, I assured him that it was not me and always put premium in it during my short ownership period.

 

I have an older car that knocks with 87 octane, but not with 91+

I would not risk using regular gas in the C7.

 

Wow.
It only cost refiners 8 cents to refine up to premium gas?

Most gas stations around here charges 40 - 50 cents more for premium, that's 20 - 25% higher than reg.

Don't mind paying for premium, just hate being ripped off...

 

Bet you the car would run fine on 87 octane. That motor will pull timing without knocking, but you will lose power for sure.


Guess you wouldn't want to fuel my race car. 110 is a minimum I can run..

 

Ripped off depends on how you look at it. It’s common in any number of products for the price of top line goods to be substantially higher than the extra cost of making them. The problem is really with human nature. Some people equate price with quality, and want the very best, so are willing to pay very high prices to get it. In the case of gas, this issue applies to all the people who buy premium for cars designed for regular. They are actually gaining absolutely nothing for their money. Octane higher than the engine’s design does not give more power or mileage, and the additives (and thus engine cleanliness) are the same in all of a company’s grades too. If a person driving an 87 octane car is knowledgeable, he will spend a few extra pennies to get 87 octane from a top tier brand, rather than a few extra dimes to get 93 octane from a non-top-tier brand. Most of the premium is sold to people driving cars designed for regular. So to whatever extent there are victims in this, the victims are the few who drive cars that actually need premium. But don’t blame the oil companies. They are simply doing the standard marketing ploy of charging more than cost for their premium product for the two reasons of maximizing their profit and being able to sell their base product at the lowest possible price.

 

[QUOTE=KenHorse;1588920057]Typical fill for an "empty" C7 is around 13 gallons. The difference in pricing between "regular" and "supreme" is typically what, 20 cents a gallon? That's $2.60 difference.
QUOTE]

20 cents a gallon, I wished. Here in Houston, it's 50 cents to 90 cents a gallon more than regular. However, I use only supreme in my 2015.

 

I would follow what is recommended by the owner's manual. They put the recommendation in there for a reason - to protect your engine. It's not worth the risk to run a lower octane gas IMO.

 

My latest app addiction, I check that stupid thing even when I don't need gas!

 

No, SMFCPACFP is correct. The higher the compression ratio, the higher octane fuel that you need. The more sophisticated computerized engine controls in today's cars allow for much higher compression ratios for a given octane level than could be used in yesteryear's cars, but the physics is still the same.

 

If you can afford the car, you can afford premium.

 

I use top tier premium because I found out the hard way what knock can do. I bought a used C4 15 years ago that had a failed knock sensor. I didn't understand what knock could do, and it did knock a bunch coming home up the mountain. A couple of years later I decided to rebuild the old L98 and every one of the pistons had cracks in the skirts. My machinist said it was likely the knock that caused it. Those poor old pistons were rattling around in there, knocking on the walls of the cylinders. No knock allowed in my C7!

 

Amazing....simply amazing. I wonder if the same logic could be used to eat cat food sandwiches instead of tuna. After all, it's cheaper.

 

Hey, that'll get your "engine" purring.

 

FWIW: Owners manual says premium required. Fuel door says premium RECOMMENDED.

Which one do you think more people see?

I don't know why people come in here and state the obvious. Its obvious the person can afford the gas. The question here is whether he/she is getting any value for it.

 

Do what's in the manual unless it was amended (ie. 500 mile oil change in Z51 cars).