I am having trouble finding top-tier gas stations with premium in my area, they all seem to be out and no idea when more is coming.

In case, I can't get top-tier-premium, is it better to get top-tier-89-octane with additives or non-top-tier-premium?

I guess I can always get a detergent additive as well for non-top-tier-fuel.

What do you suggest? Thanks

 

I would for sure use non top tier premium over 89.

 

Non-Top Tier Premium and then use Top Tier Premium when it is available again. If it is going to be several tanks on non-Top Tier then put some Techron in.

 

Octane first

 

Just try to use 91 and above and don't lose sleep over it.

 

No way! Octane is key. If you are worried about it do what I do and add a bottle of Techron about every 4th fill! That is essentially what it says in the Owner's Manual only more often than it suggests! Quoting:

"TOP TIER Detergent Gasoline is highly recommended for use with your vehicle. If your country does not have TOP TIER Detergent Gasoline, add AC Delco Fuel System Treatment Plus−Gasoline to the vehicle’s gasoline fuel tank at every oil change or 15 000 km (9,000 mi), whichever occurs first."

Top Tier was more important with port injection to help keep PCV crankcase "stuff" from causing carbon deposits on the back of the intake valves (called coking.) Now with direct injection gasoline does not help as it does NOT go over the intake valve backs. Techron was Chevron's gasoline additive and no doubt still is in their additive gas to make Top Tier. When their patents were still effective other gas companies used it, now most have their own "cleaning additives." It does help keep the injectors and some help in keeping the combustion chambers clean.

The AC Delco Fuel System Treatment (last I looked) had the same SDS (Safety Date Sheet) chemicals as Techron. Since AC Delco just buys the stuff and has their name put on for a premium price, it could be the same! I buy mine at Walmart for <$5/bottle. One bottle per tankful.

Octane is critical, Top Tier nice to have and if not, as I say, a bottle of Techron every ~4th fill, don't wait 9000 miles!

 

I expect many negative responses here from what I am going to divulge here so understand that I am only the messenger.
A friend, who owns a new Porsche which requires high octane (premium) gasoline, uses only regular gasoline in his Porsche and he has been doing this for many years on all his cars which all have required high octane (premium) gasoline.
He swears that all his cars have run properly without any issues and the only thing he has noticed is very, very slight less power which he says is very negligible and hardly noticeable.
He says that today's very advanced sensors in the car automatically adjust to the lower octane and this will never do any harm or any damage to the engine.
I can see why he has been doing this surprising action as he is saving at least 60 cents/gallon if not more, cost between regular and premium.
I remember when the difference used to be only 15-20 cents. How life has changed.
I expect to hear that he is penny wise and pound foolish,
Has anyone ever tried to use regular gas in their Corvette (which has always required the highest rated premium gas) ? How has your experience been by doing this?
Will using regular gas really do any damage to the engine besides having slightly less power?
Thank you.

 

Sorry, not trying to offend. I think I'll stick the the Corvette Engineers over "A friend of mine swears...."

 

91 minimum octane for the Corvette, although you may get by with less at altitude. But running less than 91 could cause damage that wouldn't be covered under warranty.

 

2020 Owners Manual:
2021 Owners Manual:
2022 Owners Manual:

 

Are you willing to throw those dice to save $10 on a tank of gas?

 

I would get non-TopTier gas and add Chevron Techron.

 

the 2014 LT1 even said: Use premium unleaded gasoline with a posted octane rating of 91 or higher. If the octane is less than 91, you could damage the engine and may void your vehicle warranty. If heavy knocking is heard when using gasoline rated at 91 octane or higher, the engine needs service.

Now they have pushed that 6.2 Liter engine even further and as Zymurgy showed it will detune even with 91 octane. Can only get the MAP to richen mixture and pull out timing just so much! A word I seldom use: STUPID to use less than the highest octane in your area. In my case it's 93, understand in places like CA it's 91. If you can't get that park the car!

Possible whatever Porsche his friend had there was room for lower octane tuning in the air/fuel/timing MAP.

 

One time when driving my C-7 on a long trip, I was almost empty and only regular 87 octane was available. I put 10 gallons in and drove easy. Anytime I had to go up a slight hill, the car would start to knock. I downshifted to ease the load on the engine. I ran the tank almost empty before I filled up with 93 octane. But it took a second tank before the performance returned to normal.
The point is I can see how easy it would be to damage the engine.

 

Thanks for sharing your experience.
It looks clear that it is best to use the highest rated octane gasoline that is available in your area as the Corvette engine is only hungry for high octane.
Looks like Porsche's sensors are different and are capable of adjusting in handling lower octane, something that Corvette's sensors are incapable or not designed for.
The highest octane in my state of Colorado is 91, like California. I would have liked to experience driving with 93 octane, if and when that opportunity becomes available.
I will will continue using premium gas when my 2022 C8 gets delivered as I have no intention in damaging its engine.
I have always used premium in my previous 2016 C7 and will always keep using premium in my new C8.

 

I always say there are certain things I do not try to save money on, like ammunition, condoms, and lawyers.
Buying high performance vehicles then using the wrong gas to save a few dollars is really not smart, to say it in nice way. Its epically stupid.

 

I live in Colorado Springs and drove my car home from Michigan. When I hit 500 miles I got on the car once at about 1,000 feet with 93 octane. The car here at 6,500 feet is a different animal on 91 octane, because of the altitude. My wife’s BMW M340i X-Drive feels about the same from 20-70 mph. But it is turbocharged and the C-8 is not. To best described it, my C-8 at 6,500 feet feels a little slower than my C-7 Z-51 at sea level. But off the line the C-8 would smoke my last Z-51 C-7. As far as every other aspect the C-8 is the best car I have ever owned.

 

Nonsense. The "sensors" are knock sensors. They detect detonation (knock} and the system makes adjustments to help eliminate it. The problem is the detonation has to occur before the system can adjust. Detonation is bad. Just because your friend is doing this in his Porsche doesn't mean it is advisable nor free of potential damage. Altitude helps offset octane requirements.

 

Knock sensors can only retard timing so much. If you are on too low an octane the car will knock . if you push beyond the sensors capability it will knock and damage can occur.

 

An LT2 has 11.5:1 compression ratio, only so much pulling of timing to deal with that.