I am always more concerned about the gas station itself, if it is an old dilapidated looking station I assume they have crappy tanks and pipes so I go somewhere else. I try to lead with Shell, Mobil, or Chevron but if I have to use Citgo, 7-Eleven, Racetrac, or some other provider I am not scared. It won't hurt anything.

I saw an interesting documentary a bunch of years ago about Petro and the national pipeline that distributes the gasoline from the refineries to the rest of the US. When Shell puts a load of 93 octane into the pipeline in Texas they can then pull out 93 octane immediately on the other end, say in New England. It may or may not be gasoline they put into the pipe, everyone is putting gas into that pipe. It is a bank system, same as you putting 20 dollars into your bank, you can pull 20 out anywhere else and it isn't the same bill.

The main difference in gas from what that documentary explained was the additives. This is my understanding of the process and since it makes sense I am rarely concerned with gas.

The idea of gas going bad is always amusing to me. I leave gas in my Jetski for 6 months and crank it up with no problem. It has a carb. A buddy of mine has watercraft also, every time he has a problem starting he thinks it is bad gas, drains the tanks, does all kind of cleaning stuff for the carbs. It always ends up being something else, I find it amusing and bust his chops every single time. I think he has finally abandoned that though.

 

I believe it was on this site, but someone had a brother who was an engineer for Shell who said gas is designed for 2 year shelf life.

 

I do the same thing wit my Craftsman Edger (use about twice per year) but I add Stabil in my portable gas container. I do see evidence of varnish coating inside the carb tho over time. Same thing in my motorcycle and that gets ridden multiple times per week. I clean out carb every few years.... I've seen gas go bad in a portable container. Took a couple years though. I bought a 1966 Thunderbird once that was sitting for 10 years and boy was that gas bad!

All this said though, I think Mikey's comment on the air getting to the gas is really the issue. Plus it takes a long time.

Love this forum. Ya tend to learn a lot

 

My problem was not so much 'bad gas', but that stupid ethanol. I parked my Honda Magna motorcycle over the winter without draining and running the carbs empty a few years ago. Next spring when I went to start..... ran great on full choke but not at all on idle. Motorcycle shop knew about a lot of people had the same deal and took my carbs off. All the idle circuits were gummed up with dried-out ethanol goop. That was a nice $480 lesson for me.

 

The ethanol has played hell with boat gas tanks also. In my motorcycle, jetski, jeep, other jetski, well they all at some point have had gas for long periods. Some are carb, some are fuel injected, no issues.

My generator though with 5.0 Briggs and Stratton I make sure and run it completely dry. It has just a simple jet (no carb) and the only issue is the jet will close off with crystal. Perhaps that is the varnish discussed. So gas over a very long period can cause issue, it is the 3 or 6 months I find a bit of a stretch.

 

Lots of good stuff here-- and yeah, every time I post I learn something. Thanks!
I think I'm just gonna stick with Chevron (it was my go-to brand years back) and maybe dump a can of BG44K in once a year or so, and otherwise forget about it.
I will say, though, that one of the upsides of having an XKR as your daily driver is that a lot of the issues I see on this forum don't always apply. I'll have burned through this tank of gas in a week, tops.
Lots of other things to obsess about on these cars....
(anyone want to talk rear foglamps?)

 

Yeah, I buy Techron when it is on sale. Since my motorcycle tends to sit quite a bit I like to run a bottle through periodically. One time it ran a bit rough, so I used it and it cleared up quickly. No issue since, but it seemed to help the injectors. Same with my Jeep, one time it ran rough, thought I had a problem with a cylinder, dumped in some Techron and voila, like new. Haven't used it in years and only had it happen once per toy in a 5 year period.

 

Long before Arco became the cash or debit card only retailer of gas, they were the "top tier" gasoline retailer known as Atlantic Richfield (Richfield gas stations were probably the most common stations in Los Angeles and California when I was a young man). They changed their business model to get out of the credit business. The quality of their gasoline products didn't change. Although I rarely stop at Arco stations even though they are usually a little less expensive, by the time you use a rewards card at Shell stations where you save anywhere from $.10 to $.40 per gallon and you can use your credit card, it's just not as convenient to use Arco. I was never worried about the quality of their product. It was probably a rumor started by the advertising department of another oil company.

 

From an old oil refiner:

Yes the gasoline base is essentially the same. Some have more ethanol etc

The key difference factor is the deposit control additive (valves and injectors). There is a standard test done on BMW engines that clearly differentiates them

Chevron is clearly best

Shell/Esso/Mobil next (OK)

Arco/BP/Sunoco/Phillips etc next (OK)

Then... Beacon, Ultramar, Valero and a bunch of others (use at own risk)

I wouldn't trust the additive in Kum and Go's gasoline. Certainly not with a stick shift!

Heres a bit of reading

SwRI Qualifying Fuels to Avoid Intake Valve Deposits Brochure

and

https://www.astm.org/Standards/D5500.htm

 

Here's the full AAA technical report on Top Tier fuels. It makes a pretty compelling case for using Top Tier. The Gas Buddy app indicates stations selling Top Tier.

 

I read through most of the study but unfortunately, it doesn't disclose the names of the "top tier" gasolines. So I went online to find which stations sell top tier gas and here is what I found (and yes, ARCO is a top tier gas retailer).
Buying gas from a station on this list is better for your car | Clark Howard

 

Quote from key findings on page 24 of the study

2. Based upon secondary research findings, long-term use of a gasoline without an enhanced
additive package can lead to reductions in fuel economy of 2-4%, drivability issues, and
increased emissions.

Compelling to me is not 2-4% difference in fuel mileage when comparing the best to worst case.

 

Folks you have to go beyond the "Top Tier" class and realize that some Top Tier gasolines are a lot better than other Top Tier gasolines. Whish is why I stand behind Chevron (and no, I have no connection). For those tl:dr ADD folks, look at this graph within the referenced AAA report. Clearly it shows Top Tier gasolines as better - But Top Tier #5 has SEVEN times the valve deposits of Top Tier #6. Good is good but better is better.

 

If the real world difference between the best (9.6mg.) and the worst (827.2mg) is only 2-4% change in fuel economy, the difference between 68.8 mg. and 9.6 would be to small to accurately measure.

Graphs are nice to look at but there has to be some critical analysis of the data.
Remember that the deposits are being measured in milligram (1/1000 of a gram). For the non-metric folks the worst example with 827.2mg is equal to 0.02917862 of an ounce.

 

And, with respect, critical analysis would say that economically you are better off buying a Toyota Corolla than a Jaguar XK. If you buy the best car, buy the best fuel.

Oh, wait a minute, your sig says S-type Ford Carry on.

 

Hey look at that!

We're both Canadians and we both have Jags with more or less the same Ford content in them (virtually zero WRT the engine).

If a brand of fuel makes no tangible difference what makes it 'the best' or even 'bette'r?