TOP TIER - High-quality Fuel Performance Standard - TOP TIER™

TOP TIER is developed and enforced by some of the leading automotive manufacturers and supplied by participating fuel retailers.

www.toptiergas.com

Well OB since start of gen 6, IIRC, has had DI and other individual models even earlier, so I am glad to see there is now "finally" a fuel standard supposed to be better for DI.

But i can’t find anything about TT+ on the TT website. Keepin’ it a secret🙂.

I thought maybe they were trying to find a way to sell an additional price "tier" of gasoline, but googles says there won't be a separate higher price top tier+ product, it will all be the + product. Also looks to me like 2025 is when they published the standard, somewhere, but the product will be some way behind. 🐢

I'll just keep on letting the subaru dealer sell me that rocket fuel additive they recommend so highly, for $29.99/pint. 🚀🚀

 

TOP TIER - High-quality Fuel Performance Standard - TOP TIER™

TOP TIER is developed and enforced by some of the leading automotive manufacturers and supplied by participating fuel retailers.

www.toptiergas.com

Well OB since start of gen 6, IIRC, has had DI and other individual models even earlier, so I am glad to see there is now "finally" a fuel standard supposed to be better for DI.

But i can’t find anything about TT+ on the TT website. Keepin’ it a secret🙂.

I thought maybe they were trying to find a way to sell an additional price "tier" of gasoline, but googles says there won't be a separate higher price top tier+ product, it will all be the + product. Also looks to me like 2025 is when they published the standard, somewhere, but the product will be some way behind. 🐢

I'll just keep on letting the subaru dealer sell me that rocket fuel additive they recommend so highly, for $29.99/pint. 🚀🚀

The stuff you dump in your fuel tank, or top-tier plus, will help keep your fuel system and combustion chamber cleaner. It will do little to nothing to prevent carbon buildup on the back of the valves. The fuel never touches there. The only thing that seems to help to any substantial degree is a fuel system with port injection in addition to direct injection. Top-tier.+ and additives should help with these systems, but they are not as effective as straight port injection for intake cleanliness.

 

https://www.toptiergas.com/wp-content/uploads/2025/01/TOP-TIER-Approved-Gasoline_Deposit-Control-Performance-Standard_Rev-G.pdf

 

Excellent! Thanks

 

top tier, it probably just has something similar to lacquer thinner in it to KEEP THINGS CLEANER.

Everyone on the internet, including SCOTTY KILMER, know lacquer thinner will make any modern engine clean as a whistle.

DO IT TIL ITS SHINY

 

The website isn’t the best, have to dig for links. They’ll fix it at some point.

 

"Now, with AI!" Finally, those intake valves will get cle.. Oh, wait.

 

How do the detergents get to the back of the intake valves? I am assuming we are talking about cleaning the valves or preventing the deposits from attaching to the valse.
Will the additives in the fuel prevent crankcase vapoers from adhering to the intake valve stems? Please explain the science.

 

How do the detergents get to the back of the intake valves? I am assuming we are talking about cleaning the valves or preventing the deposits from attaching to the valse.
Will the additives in the fuel prevent crankcase vapoers from adhering to the intake valve stems? Please explain the science.

Great questions! It does appear that they are saying the vapors will be less prone to build up on the back of the valves. Remember when top-tier gas first came out and they had pictures of valves on engines that used top tier and engines that did not. That was proof it worked. The proof will be in the pudding. Time will tell.

 

Re: Top Tier Plus....

If you have a Direct-Injection engine, I don't see any fuel additive can reach the back of the valves to keep them clean because the air-fuel mixture completely by-passes the valves and (like a diesel) is injected directly into the combustion chamber. So-called Port Injection adds fuel (and its additives) before the air-fuel mixture reaches and and flows past the valves.
That said, I'm open to the possibility that some chemistry may yet be able to keep the valves clean -- chemists have done some amazing things.
Nevertheless, I'm happy to sill have Port Injection on both of my vehicles -- and (1) I only use the premium grade* (92 AKI, here) of Top Tier brands (Shell is my local dealer); (2) I also add a bottle of Techron to my tank every thousand miles or so; if I know my car won't be used much (and will be sitting with a full tank) I happily also add a dose of BioBor EB (to combat ethanol water separation and as an additional cleaning agent. All in all, I think I'm doing right by my valves
[ * when I lived in N.J., the difference between 93 and mid-grade was about a $1; here in CA where I've lived for the past decade or so, the difference is only about $.10 (a dime). I'll never understand that difference between the coasts, but I'm happy to afford that pittance extra to always use the highest octane if it means more detergent (as Shell claims), and performance (because I live in the mountains with both steep grades as well as high elevation, both of which make knock more probable).]

 

If you have a Direct-Injection engine,...

I forgot to add that some high-end manufacturers such as BMW are adopting a combination Port-and-Direct Injection -- i.e., their engines provide fuel through both pathways. But I haven't heard the reasoning -- I can't believe that they're doing this "only" to save their customers the costs of regular valve blasting, but I don't know of any other benefit in light of Direct Injection being so much more efficient.

 

The subject of this thread is the role of gasoline in keeping a direct injected engine clean, and I’m excited to learn how the fuel marketers will satisfy the new top tier plus requirements.

These new requirements were not created as a stopgap solution for engine manufacturers omission of port injection. Port injection doesn’t address the root cause of intake valve deposits and washes the contaminants back into the combustion chamber. This is why some legendary engine builders like Honda do not use port injection as an approach to control intake valve deposits. If port injection is treatment like cholesterol medication, our goal should be to not require it and focus on the variables of prevention.

The engine has to be designed to minimize intake valve deposits, and the inherent reliability of those design characteristics must be maintained throughout the engine lifecycle. Regular oil changes remove wear debris and unburned hydrocarbons suspended in the oil as well as protect the timing chain, piston rings, cylinder walls, and intake valve seals. Regular spark plug replacement and premium/quality fuel helps to ensure complete combustion.