You're welcome. I'm glad that you enjoy it.

You're welcome!

Thank you. It really does make a difference.

You're welcome! It's one of those things that I wouldn't have thought much about either if I hadn't been in so deep with the experts.

Thank you for your comments. In my area (SE and Mid-Michigan), the Top Tier labels are rather prevalent. Most of the stations that I use that are certified have them. But, yes, downloading the list is the best way to know. I think BP was once on the list, but as you say, they don't currently certify and claim their propriety additive is great. They are probably right, but how do you know if the advertising is true? I agree that the base fuel is a commodity and the additives are the critical part. I would just caution that I am not sure more additive is better. There may be an optimum level. Many people believe in "More's Law" i.e. if a little's good, more's better... As I spent many years in product validation, it needs to be proven that more is actually beneficial. My guideline would be that if all grades of a brand meet Top Tier and their premium has more additive-that is sufficient proof. I think the Top Tier validation test is accepted by the engine manufacturers because they have data that it works.

A mobil station by my house does not have signs or stickers that state too tier, mobil states top tier but no sighns and i wonder if they have it

You're right that oil coming down the valve guides is a significant source of deposits on these '80s engines. I don't know about the effects of alcohol. In the '80s it was still optional and many or most people didn't use it, plus it typically is a solvent or detergent itself. Too much will certainly cause damage to fuel systems and some injectors. There were service bulletins right from the start on injector issues on my '85. Gasoline is a very complex blend of hydrocarbons and I think it took a number of years before the industry understood the effects of gasoline breakdown in injection systems. I recall a discussion in the late '90s with a fuels engineer who was explaining a field problem he encountered. He said the problem was that olefins in a specific fuel from a specific refinery were polymerizing. And without thinking, I asked for a little more explanation. He asked me if I knew olefin fabric (a polypropylene thread). I said yes, and he indicated that the liquid olefin chemical content in the fuel was becoming solid plastic. DUH! That will plug injectors...

Most welcome

Yes, Shell is on the list and a good choice.

You're welcome. Yes, the rating systems are different. There are two basic methods of measuring octane rating, one is called "Motor" and one is called "Research". In USA we use (Research + Motor) / 2. I believe your system is just the Research value. The conversion is usually considered to be about 4 points, so USA 87 should be 91 in your terms. In the US, we first used E10 in the late 1970s as a fuel extender when we had fuel shortages due to global embargos and so forth. It was called "gasohol" in the beginning. I used it in the Cobra Jet 428 because it really needed good premium fuel. Our standard in the early 80s in USA rating system was 87 no-lead, 89 leaded regular, and 91 or 92 octane no lead premium. One of the major companies was offering a leaded 91 octane E10 fuel. The 428 was built for leaded gas, so I went to that and reduced the base timing a little. It was a treat when 93 and even some 94 octane rating fuels gradually became available. The rest of the E10 story is that some people in authority think that E10 is cleaner burning that E0 and they began to force it. Old pre-computer cars tend to run a bit leaner, but those with O2 sensors really just adapt. In any case, we went from a day where the fuel was labelled and we could choose E10 or not to the current time where in my state E10 is mandatory in all grades. There is E0 available under some special rule as "recreational fuel" intended for boats and small equipment, but it's quite expensive, only at a few stations, and only 89 or 90 octane. I did start with it in my IROC until I made it through break-in and was sure that all the systems were working properly, then I made test runs with E10 and really don't see much difference. There is a little increase in fuel consumption, but not enough to worry about. GM originally intended these engines to run on 87 as a standard. I have run both 87 and 89 for comparison, but haven't seen much difference there. In principle, the knock sensor ought to allow more timing with 89, but I didn't see much effect.

I agree. Sustained use of the right fuel is important to clean up the system and keep it clean. A bottle of the right cleaner solvent can help take care of short term problems, but having the right fuel is better over time.

I use only Top Tier gas in my personal vehicles whenever possible. If I'm traveling and get caught with an odd tank full, that is the exception. My general rule is to follow the manufacturer's service schedule on everything. In my case, GM doesn't recommend a regular fuel system additive in my vehicles, so I don't normally use one. The data I have seen for the Top Tier gas is that it has both a clean-up function and a keep clean function. My local dealer offers "fuel injector cleaning" as a service and I keep turning it down under the basic premise that GM does not recommend this as a regular service. My caution as a retired product engineer is that there are times where more of something is not better. My view is that something I call "More's Law" (if a little's good, more's better...) can be a poor approach. For example, with fuel injectors, it's possible to clean the injectors /valves and just move the deposits downstream into the combustion chamber. Conversely, IF a vehicle has a problem and begins to have driveability issues or set OBD codes that are related to misfire or fuel system errors, then I would consider cleaners. My preference is Chevron Techron because I saw good results at cleaning injectors when I was in the business. I have used Techron in carbureted small engines with problems such as intake valve sticking and cleaned them right up. My alternative would be a GM branded product. If you own a different brand vehicle, I would lean toward their recommended product. Others may be good, I just don't know. I have also seen a GM service bulletin for the above conditions that prescribes a top engine cleaning with a specific tool and process along with a fuel injection system cleaning. Then a recommendation to use Top Tier fuel in the future.

​@@bitsofwisdom460 Not a stone unturned. I love this man! Thank you so much! My Dad seemed to live the Motto, "A little bit does a little good but a whole lot does a whole lot of good" He broke many bolts that in turn needed to be drilled out.🙃 No need for a response.

I hadn't caught that Kwik Trip dropped out. I used to go to them when I was in Wisconsin. That's too bad.

You're free to do as you wish, but I don't have any data on supplemental injector cleaners. Some may be good, but some may actually be detrimental. The data indicate that the Top Tier fuel does a very good job. If I had a vehicle with a known problem I would try it with Chevron Techron (limited data to support), otherwise run good gas and leave it alone. In my line of work, my team ran many vehicles and lab engines (GDI) through lifetimes of operation for durability testing (up to 175,000 miles). We didn't do injector service or use additives. I was invited to review those engines when the engine design team took them down after test. No significant issues that I can recall. Doesn't mean that there wasn't any deterioration over life, but not enough to cause problems. I have multiple GDI family vehicles in excess of 125,000 miles without any injector problems on Top Tier fuel.

@@bitsofwisdom460 my car had been sipping exclusively on Toptier gas all it's life (Audi Q3 2020) at around 50 000 km I noticed my gas mileage was not as good ,about 10% up. When looking into fuel fuel trims in OBD2 reader they were constantly 12-14% positive. So I did put Gumout PEA based fuel cleaner and everything returned to baseline after one tank of treated fuel. My brother experienced exactly the same on his 2021 Subaru Outback even tho he was not consistent on using Top tier but he was always using a good brand of fuel advertizing detergency just not Toptier licensed.

@vwbora26 Well, that's a good reason to intervene, and if you had good success, keep going. My small block Suburban is past 50k miles and has no sign of decreased fuel mileage at this point (and I watch closely). There are no other signs of an issue in driveability. There may be variation between manufacturers. I know the GM fuels engineers were deep into Top Tier fuel and the test data and performance in their products.

I appreciate your opinion, but there are several approaches and limitations. Top Tier has nothing to do with ethanol. You can buy 90 REC fuel that is Top Tier. As to running ethanol in classic cars, yes I do it regularly with stated precautions. The main problem with E10 is humidity in the air space above the fuel - hence, empty or full when sitting for long periods. The Cobra Jet has been running E10 for most of the last 40 years without any issue. I fill it in late fall with double dose of marine grade sta-bil and it sits all winter. I had the (original) gas tank opened last summer to change a fuel sender gasket and it is clean as new inside. Practical choices are few - there isn't any 93-94 octane REC fuel around in my locale (Michigan). I know that some states have E0 premium, but not here. Yes, I know you can chase around and find AVgas or racing fuel or some other odd solution. The Camaro has a sealed fuel system that limits air exchange and humidity into the tank, so is even better set to run E10 than the Cobra Jet. I have run the Camaro on REC fuel, but it doesn't make a detectable difference in performance. REC is still hard to come by when I'm out on the road and the price premium around here is about $1.50/ gallon. My choice for now is E10 with precautions.

I must say, my wife's 77 Trans AM had been running poor for several years. We kept fighting hard starts poor running and stalling, UN-acceptable. I switched to Rec fuel, and in the last 4 years her car runs like a champ. We just got it out of storage this last Sunday and she turned it over without pumping (to get fuel up into the carb via mechanical pump) and before she could pump the throttle it started up and ran perfect. I am a firm believer now.