86 octane top tier or 87 octane not top tier?

[MavRick]

Octane requirements drop with higher altitude. Top tier is essential. If you must get non Top Tier gas add a PEA additive or mix in a bit of premium with the Top Tier 86. I wouldn't bother.

My owner's manual says to never use less than 87 on my motor. Pick a higher grade until the octane is 87 or higher. I've been in winter high elevation locations where they had 85 octane and had to get premium grade just to get the Octane I wanted.

 

[MavRick]

Yeah I’ve never seen where Top Tier makes that claim.

Top tier claims that it improves fuel economy, prevents carbon deposits from building up and cleans deposits after a few tanks of gasoline. My interpretation of that is the fuel is burning cleaner. Carbon build-up in the combustion chamber is prevented and therefore cleaner burn over time.

Edit for link:

 

[kschachn]

Top tier claims that it improves fuel economy, prevents carbon deposits from building up and cleans deposits after a few tanks of gasoline. My interpretation of that is the fuel is burning cleaner. Carbon build-up in the combustion chamber is prevented and therefore cleaner burn over time.

Edit for link:

Okay sure. But all of that is quite different then preventing valve deposits in GDI engines. Different mechanism and completely different mitigation.

 

[MavRick]

This article show the benefits of top tier gasoline. Unfortunately it didn't mention which engine and whether it is a direct injection. It seems the benefits are worth it. What are the mitigations for direct injection engines?

https://www.consumerreports.org/car...r-gasoline-worth-the-extra-price-a7682471234/

 

[kschachn]

This article show the benefits of top tier gasoline. Unfortunately it didn't mention which engine and whether it is a direct injection. It seems the benefits are worth it. What are the mitigations for direct injection engines?

https://www.consumerreports.org/car...r-gasoline-worth-the-extra-price-a7682471234/

First and foremost it is a design issue. But the only one related to the user is the oil.

 

[garageman402]

There is, but I don't have a membership so I've never checked what they have.

Depending how much gas you use, the amount you save at Costco gas stations alone could cover the cost of membership, check the prices, drive through there when they are not busy (rarely) or closed.
As far as octane, I drove my motorhome through Colorado where they have 85 octane. Most of that drive was above 6000 feet, had no issue. But top off with 87 when getting back down below 2000 feet. Texas hill country has 86 about everywhere, & the next grade up (88) is a lot more expensive. With 6-8mpg on the motorhome with no tailwind, every penny per gallon counts........

 

[GaryMX5]

There is, but I don't have a membership so I've never checked what they have.

We found that gas savings alone can pay for the membership. Then you can add some significant savings on a lot of other stuff. While it stings initially, the base membership pays for itself pretty quickly.

 

[Ayrton]

I'd get at least top tier (some brands are above it). Especially in direct injected engines with the fussy injectors. There is actually a new level of top tier soon, Top Tier Plus I think, because the newest injectors need more to be kept clean.

 

[ammolab]

As said: The thinner air at altitude gives you less dense air for cylinder filling so compression is effectively lowered reducing octaine requirements.

My 415 HP LS3 naturally aspirated Chevy V8 makes about 380HP or less at the 6500 ft ASL I live at and does not require 93 octaine. Now when I visit Houston? 93 goes in and the car goes like ..SCAT!

 

[Japanese]

I've been using the 87, but read that top tier gas contains detergents that help keep your engine clean

What does top tier gas mean? How is defined? What gas stations are considered top tier?

 

[3GTL300k]

What does top tier gas mean? How is defined? What gas stations are considered top tier?

https://www.toptiergas.com/

https://www.ace.aaa.com/automotive/advocacy/top-tier-gasoline.html

 

[Japanese]

https://www.toptiergas.com/

https://www.ace.aaa.com/automotive/advocacy/top-tier-gasoline.html

Are these credible sauces?
The second website cannot be accessed on mobile.

 

[3GTL300k]

Are these credible sauces?
The second website cannot be accessed on mobile.

Well first site is the official Top Tier site. Just Google AAA top tier and you will find their article about top tier and the testing. It's from about a decade ago now.

There's a thread in this section about the new Top Tier + standard coming out with an even higher cleaning standard.

Here:

1

Thread 'Coming soon... TOP TIER+ fuels'

Jan 28, 2025

From the horse's mouth: TOP TIER+ Announcement

• 19074
• Replies: 33
• Forum: Fuels and Fuel Additives: Gasoline and Diesel

• 
• 

 

[Japanese]

Well first site is the official Top Tier site. Just Google AAA top tier and you will find their article about top tier and the testing. It's from about a decade ago now.

I don't see any gas stations mentioned.
So what stations offer too tier gas?

Gasoline itself is one of the best cleaners of oil, grease etc. So why would you need additional detergents in it?
What part of your engines need to be cleaned by the gasoline?

Who and how would convince me that "top tier" gas is not a marketing trick to buy gas at certain places, but not others?

 

[ARB1977]

My wife’s Pilot gets what ever is available. I run a bottle of redline SL1 every oil change. The Tundra gets top tier…QT 87. That gets redline SL1 every 5K.

 

[Mainia]

SkyActive engine....... 87 for sure. Top Tier is high on my list for that car long term. You have 13 to 14 to 1 compression, having clean injector and a nice spray pattern is a plus. OR use injector cleaners every oil change if TT station is so far away it is a burden.

 

[Mainia]

First and foremost it is a design issue. But the only one related to the user is the oil.

What about PVC contaminants, I see that as a oil/fuel combo there and what about valve overlap push back? The consensus is not there, that valve overlap has nothing to do with carbon on the back of GDI valves, that would also be oil/fuel related.

 

[Wylie6G72]

According to my understanding Top Tier burns cleaner, thus less carbon to collect. It doesn't prevent carbon build up; it just slows down the accumulation of the build-up. The issue with direct injection is if the valves do get carbon build up on the backside of the valve to the point of it being a problem, there isn't anything that can be cone but to remove the valves to clean them. Probably not too important if you don't plan on keeping the vehicle into high mileage range.

You're thinking of the wrong valves. The problem with direct injection is the backs of the intake valves build up carbon deposits from PVC gasses which carries an oily mist into the intake tract. No fuel will touch this in a DI engine. I've never seen exhaust valves with carbon buildup other than a very thin layer on the face of the valve.

 

[kschachn]

And just the fact that it is GDI in the first place.

 

[garageman402]

I don't see any gas stations mentioned.
So what stations offer too tier gas?

The first site, the official Top Tier site, has station names & locations if you enter your Zip Code. It also explains what Top Tier is.

Gasoline itself is one of the best cleaners of oil, grease etc. So why would you need additional detergents in it?
What part of your engines need to be cleaned by the gasoline?

Gasoline leaves deposits as it flows through the engine, especially on intake valves & injectors in port injected & carbureted engines, injectors on direct injected engines, combustion chambers in all engines as it burns.