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Something I said in my very first Tech Article (August 2007) for the Flagler County Corvette Club newsletter. That's because GM, thus Corvette, was one of the first auto manufacturers to recommend Top Tier gasolines be used in their vehicles.
This quote is right out of the Corvette manual:
"Use of the recommended fuel is an important part of the proper maintenance of this vehicle. When driving in the U.S. and Canada, to help keep the engine clean and maintain optimum vehicle performance, we recommend TOP TIER Detergent Gasolines. See www.toptiergas.com for a list of TOP TIER Detergent Gasolines."
Fortunately, there are more gasoline retailers rated as "Top Tier" nowadays then when I first wrote the article, such as Exxon/Mobil. Note, the company must have sufficient additive in all grades of their gas to qualify for this rating, not just in their "high test" grade.
I've EXCLUSIVELY used Top-Tier gasoline for over a decade, and the research on the benefits is compelling in traditional fuel-injected engines. However, the research is also beginning to show that Top-Tier doesn't prevent the emerging problems of valve deposits on gasoline, direct-injected (GDI) engines, and all the LT engines now are GDI. In fact, the majority of modern engines now are GDI.
In traditional port-fuel injection engines, the injectors spray fuel on the valves, and the detergents in Top-Tier fuels do a good job of keeping them clean. In a GDI engine, the fuel is injected directly into the cylinders, by-passing the valves, and the same cleaning effect does not take place. The industry has recognized that new oil and fuel standards are required for GDI engines, and they are under development, but, as of yet, it's not clear what the answer is.
Thus, it's questionable that Top-Tier fuel alone can produce the same benefits in our GDI engines. It's a potentially, very large, "ticking time-bomb" w/ many GDI cars showing severe valve deposits relatively early in their lifetimes. Right now, the only solution is removal of the top-end, and mechanical valve cleaning.
I wasn't aware of this issue so, thanks to the forum.
In my area of coastal GA and SC there are major "local" cstores - Enmarket, Parker's, El Cheapo ( yes a real name), etc. that compete with the name brand gas/oil marketers.
I have been curious where they source their gas.
I have been frequenting both Enmarket and Parker's for a couple years now.
I need to investigate their source and detergent content.
It may be a good fuel from a combustion standpoint, but not from the standpoint of having enough detergent additives to keep your engine free of valve deposits over time.
I have always been a Chevron or Shell user until the C7, as it is not injected from the top, but rather into the combustion chamber I have not worried to much about using Chevron or Shell. I now use any top tier gas that is lessor expensive.
My C7 and Buick Regal GS are both doing fine with these fuels.
AAA has nothing to do w/ Top Tier. The link above was just a story written in an AAA publication. Top Tier gas is a fuel certification standard set up years ago by a consortium of manufacturers including GM, BMW, VW Audi, Porsche, and many others.
There has now been enough data collected over at least a decade to show that Top Tier fuels keep engines far cleaner than non Top Tier fuels. Sunoco is not on the least because they don't meet the detergent additive standard.
I drive an 05 Audi A8 L 4.2L and I found that after I fueled up at my local Sunoco station, it felt so much smoother to me. Then to read this article I feel like something's wrong. I only use 93 octane so now I am about to test this theory about feel and all of the car. I am going to go fill up at a Mobil gas station bc its top tier and see if I feel a difference at all. I don't mind paying more if it really makes a difference.
It doesn't make any short-term difference that you can feel. It's about long-term build up of carbon deposits on your valves over 40K miles or more.
So if you're going to now fill up with Top Tier to "test this theory," you should rethink your test. You're not going to feel any difference, and if you felt a difference just because you filled up with Sunoco, it was all in your head.
The list at the cited web site appears to be out of date.
I say that b/c it lists Amoco as one of the Top Tier brands. While that may have been true at one time, Amoco was bought by BP at least 5 years ago - Amoco as a brand name no longer exists.
At least in my area of the country, all Amoco stores were changed to BP.
(And all my Amoco stock was converted to BP)
Same with Texaco - they were bought by...Chevron, I think. Same as Amoco/BP - all stock converted to Chevron, and all stores in this area renamed to Chevron or sold to a different retailer.
Exxon and Mobile merged, as well, Stock and company renamed ExxonMobile, but for whatever reason, I think they still maintain separate store names.
07-09-2016, 10:00 PM
