FR-S may be very sensitive to bad gas.
 

Gasoline is sold by the billions of gallons. Trucks and pipelines can be old, trucks improperly maintained, and storage tanks subject to water infiltration and sediment build up. It is no surprise then when we get the occasional tank of bad gas.

But I think that there is something about the FR-S duel fueling system that makes it extremely sensitive to bad gas. I don't know if it is water or other contaminants, but more than a few of us have experienced poor performance after a fill-up. Nothing radical, but a decrease in power, and sometimes hiccups from the engine as it dials back the timing to compensate.

The question then, is what can we do when we get a tank of bad gas? For me, four fill-ups of Shell 93 seemed to be enough to clear the system. What I am wondering is whether a simple additive, like Methy Alcohol (dri-gas) will clear the system faster?

The other question I have, is whether we will experience problems over the winter? It may be that the FR-S will be unusually susceptible to vapor lock. This bears watching. It may make sense to have a strategy of keeping dri-gas handy, making sure that the tank is refilled when it is only half empty, and avoiding gas stations whose tanks have been recently refilled - a process that stirs up contaminants in the storage tanks.

I don't have the answer. However, my car ran like absolute crap after I filled up with Shell (was running Mobil before that). I happen to have 5gal of Torco Accelerator for my offroad vehicles, so I added 8oz of this to my fuel. My car woke up immediately.

For now, I'm sticking with a gas station I've had luck with. If I run into this again in the future, I'll add some more Torco.

i absolutely agree with you OP. I have noticed that different gas stations and different brands of gas has definitely affected the performance of my car, especially mileage wise.

I use HEET if you have problems.

Gets rid of the water right away.

I take aircraft fuel samples(amongst other things) for a living. We get fuel trucks coming in and out everyday. If you have ANY significant amount of sediment and/or water in the fuel you are pumping, not only is there a serious issue but you should never pump there again.

how would we test for that?
also, which gas station brands does everyone use?

Water is heavier than fuel. Therefor it, along with sediment, would sink to the bottom. Im not yet familiar with my FR-S' fuel system but assuming the pump draws from the bottom of the tank, if there was anything foreign to fuel in the tank you would likely notice it either right away or after the car has settled, allowing all contaminants to sink.

That being said, if you did have water in your fuel it would probably be minute and not noticeable.

Unless you are buying from some sketchy, backwater station that pumps out of a barrel, there are no significant differences between brands. You can follow a truck from one to another.

The first time I pumped some gas at Shell (in Dallas,TX) my car started to get annoying cricket sound for that first time at 7k miles. I pumped at another Shell and still got cricket sound. When I got back to my hometown I filled up a new tank at Circle K (where I usually go) the cricket went away. Thanks God.

what kind of things do you look for?

Additionally, all modern fuel pumps have water sensors and too much water in the fuel will trigger a trouble light. Some cars have a dedicated dash light for this, other just pop the CEL and you'd have to check with an OBD2 scanner.

thx info!

I just picked her up from the dealer yesterday and they filled it up with 76 station gas before I signed the paperworks. lucky me to get full tank before picking it up. So far no gas related issues nor chirping. Just the hot air through the vents. will have to work out the kinks.

My area has:
Chevron
Shell
Costco
Arco
Mobil
7-11
76
a few privately owned family gas stations (best for me to stay away from these? i.e. Bob's Gas in Oceanside,CA)

I will try to hit up these stations as my tank empties and maybe do a report. I am in the SD,CA north county area if that'll help demographics. May take a while cause I don't drive it like a commuter car and therefore do not need to fill up very often. However, We should make a list of brand stations, or is that a moot point since it could be a fluke?

Top Tier gas matters
 

It is true that almost all gasoline in an area comes from the same pipelines single source.

However - individual companies blend in additives to make their gas unique. That's why Exxon gas can claim higher detergent levels.

The best gasoline available in standard stations are those blends conforming to "Top Tier" gasoline standards. A while back, the major automakers, recognizing that today's engines require higher quality gas due to tighter tolerances and controls, developed the Top Tier gasoline standard.

The major suppliers of Top Tier certified gas are the following:
Chevron
Conoco
Exxon
Mobil
Phillips 66
Shell
Texaco

There are many additional regional companies that sell it. Find them at Toptiergas.com

However, not all gas stations are maintained to the same standards. Shell, for example, has a history of penny-pinching in maintenance and safety. I don't know if this applies to their stations. But often, a firm's quality standards tends to trickle from the top down. Exxon or Mobil could be a better bet.

I've been running Exxon 93 exclusively for the first 1200 miles with no problems.