Review: Ethanol Free Gasoline and Storage Additives Part 1

Let me start with a little bit of background. Growing up, I detested gasoline powered technology. Except for the cars my parents drove, nothing gasoline powered ever started properly, let alone on the first try. When it came to my toys, my gas powered free-flight helicopter and control line planes took forever to get them to start properly. Then when I was old enough to mow the lawn, I dreaded having to start the mower. It would take dozens of pulls to get that sucker started, especially at the beginning of the summer when the mower hadn’t been used in months.

This frustration continued until I bought my first home in 2012. The prior owners provided a mower that came with the house, but I needed something most substantial, so I bought a walk behind trimmer mower. It worked fine the first season, but then when I tried to used it the second season, it wouldn’t start. I know it had oil and gas (I remember that it had at least half a tank of gas when I stored it the prior fall), so I couldn’t figure out what the problem was. If you know anything about gasoline powered lawn equipment, you already know what I did wrong here.

Eventually I emptied the gas tank, poured in fresh gasoline and tried it again. After a few dozen pulls on the starter and several pushes on the primer bulb (or maybe it was a purge bulb, I don’t remember), it started just fine. I learned a valuable lesson that day and the more power equipment I’ve purchased, the more I’ve learned about how to properly care for and store them when not in use.

Now, all of my outdoor equipment, from my Stihl BR600 Magnum backpack blower to my cheapo Bolens BL110 string trimmer all start perfectly, within just a few pulls on the starter. They sometimes start on full choke. But one thing I still haven’t figured out or fully understood is gasoline storage.

I’ve done a lot of research online about the drawbacks of ethanol gasoline, as well as how gasoline is a difficult fuel to store for anything more than a few months. But most of what I’ve found is anecdotal or without any reference to experimental data. So I wanted something more tangible and concrete as to why storage additives work and what ethanol gasoline is the scourge of lawn equipment everywhere.

Therefore, I decided to conduct an experiment. I would compare how E10 gasoline compared to ethanol free gasoline with respect to long-term storage, as well as examine a few of the more popular gasoline storage additives on the market today.

I decided on using Sta-bil Storage and PRI-G. If I had the time and money, I would have tried a few more additives, such as Sta-bil Marine. But the more I tested, the more fuel and equipment I’d need. Basically, each new additive I tested would result in roughly an extra $25 in the cost of this experiment and supplies. It also required the storage of more gasoline in the garage, so I had to draw the line somewhere.

This is the first blog post in a two part series where I explain my methodology and document the beginning of this experiment. In two or three years, I will finally test my samples and upload my results for you all to see.

Methodology: Samples

I wanted to test both E10 gasoline versus ethanol free gasoline, as well as the Sta-bil Storage and PRI-G additives. Therefore, I originally decided on using the following 6 samples:

- Ethanol free gasoline with no additives

- E10 gasoline with no additives

- Ethanol free gasoline with PRI-G

- E10 gasoline with PRI-G

- Ethanol free gasoline with Sta-bil Storage

- E10 gasoline with Sta-bil Storage

After doing some research about PRI-G, I read that it could keep gasoline “fresh” for many, many years (even indefinitely) if you added more PRI-G every 6-12 months. So I decided to add the following sample:

- Ethanol free gasoline with PRI-G, then more PRI-G every 9 or so months.

I’ve also heard the benefits and enjoyed the convenience of TruFuel, so I decided to put their 2 year and 5 year storage claims to the test. Therefore, I added 2 more samples:

- 1 can of TruFuel 50:1 unopened (advertised as lasting 5 years in storage)

- 1 can of TruFeul 50:1 opened (advertised as lasting 2 years in storage after opening).

This gave me a total of 9 samples to store for several years and test the results.

Methodology: Storage Containers

Now that I knew I wanted to test 9 samples, I needed 9 containers. Because TruFuel comes in a can, I didn’t need separate containers for them. That left 7 more containers to find. I debated for a while on what to use.

I was originally going to use liquid fuel stove fuel bottles, but decided not to because most of them wouldn’t handle E10 gasoline very well (they’re typically made out of an aluminum alloy) and the ones that could handle E10 were more expensive than 1+ gallon fuel cans. But the biggest reason why I decided against fuel bottles was because it wasn’t a realistic method of storage.

No homeowner or landscaper is going to store his or her lawn equipment fuel in a 800 mL, 1 liter or 1.5 liter camping stove fuel bottle. And from personal experience, I know modern gas cans are very airtight, so much so that they bloat as the gasoline breaks down and partially turns to vapor or gas (thanks EPA!). Therefore, I decided on using a conventional gas can that you could find any hardware or big box store. I choose the smallest size available, which is the 1.25 or so gallon size. I went with the Ameri-Can from Scepter due to their low cost (under $9 from Walmart).

Caption: Brand new Scepter (Ameri-Can) 1+ gallon gas cans

Attribution: Author’s Own Work

I know that oxygen and gasoline don’t mix well when it comes to storage, so I knew that I would fill each gas can mostly full. As a result, I decided on putting 4 liters in each gas can (I used liters because 4 liters was a tad more than 1 gallon so there’s less air space in the gas can. It would also provide enough fuel for testing later on and would make figuring out ratios with the Sta-bil and PRI-G easier).

Summary of Samples for Testing

- Unopened 50:1 TruFuel

- Unused, but opened 50:1 TruFuel

- 10% Ethanol gasoline

- Ethanol free gasoline

- 10% ethanol + PRI-G

- Ethanol free + PRI-G

- 10% Ethanol + Sta-bil

- Ethanol free + Sta-bil

- Ethanol free + PRI-G with 15 mL additions of PRI-G every 9-12 months or so

Samples for Testing: TruFuel

Caption: The 2 cans of 50:1 TruFuel for testing

Attribution: Author’s Own Work

Samples for Testing: Gasoline

Caption: Ethanol Free Gasoline

Attribution: Author’s Own Work

Caption: E10 gasoline

Attribution: Author’s Own Work

I also took the time to confirm that the E10 gasoline had ethanol and that the ethanol free gasoline had no ethanol. I did this by taking 200 mL of gasoline and adding 20 mL of purified water.

Caption: E10 gasoline with water

Attribution: Author’s Own Work

Caption: Ethanol free gasoline with water

Attribution: Author’s Own Work

Notice something interesting? After adding 20 mL of water to the ethanol free gasoline, I got 20 mL of water out. The graduated cylinder shows about 18.5 mL due to a little spillage on my part.

But when you look at the graduated cylinder containing the E10 plus water “mixture,” I was only able to remove about 25 mL of water and ethanol mixture. Assuming the 200 mL of E10 gasoline had 10% ethanol, that meant there should be 20 mL of ethanol in the E10. Combined with 20 mL of water, and I should get at least 35 mL of clear liquid separating from the gasoline (I know that if you add equal parts of water to ethanol, you get slightly less volume than double the volume of either ethanol or water – thanks Bill Nye!). But notice that I only got 25 mL. This means that the E10 gasoline was only 2.5% - 3.5% ethanol based on my estimate.

This isn’t to say the gas station mislabeled their gas. After all, their signs always say “this gasoline may contain up to 10% ethanol.” And I’m not surprised the gasoline doesn’t have 10% ethanol, but I am surprised it only has as little as 2.5% by volume. And no, I didn’t have contamination from ethanol free gasoline still in the pump and hose because I purchased this E10 gasoline from a station that only carried E10 gasoline.

If my calculations or understanding are incorrect, feel free to correct me in the comments below. Regardless, my ethanol free gasoline was truly ethanol free and the “E10” did have a measurable amount of ethanol in it. In case you’re wondering, I purchased both types of gasoline during the afternoon of May 30, 2018 and created and stored the samples on the evening of May 31, 2018. Both types of gasoline were rated 91 octane using (R+M)/2 method.

Samples for Testing: Additives

Caption: PRI-G for small engines

Attribution: Author’s Own Work

Caption: The back of the PRI-G showing its package date of January 6, 2017

Attribution: Author’s Own Work

Caption: Sta-bil Storage

Attribution: Author’s Own Work

Caption: The back label of Sta-bil Storage showing codes I can’t decipher.

Attribution: Author’s Own Work

I purchased the Sta-bil from Lowe’s on Monday, May 28, 2018 and ordered the PRI-G from Amazon.com around the same time. Per http://priproducts.com’s FAQ page, PRI-G is supposed to last indefinitely in an unopened container. Then once opened, it will last 3 years.

I chose the small engine formulation of PRI-G because it would be a lot easier to measure out the proper ratio for gasoline. Regular PRI-G has a 2000:1 ratio, so my 4 liter gasoline sample would only need 2 mL of PRI-G. On the other hand, PRI-G for small engines requires a 320:1 ratio, so I would only need to mix 12.5 mL (I actually measured out 15 mL, and I’ll explain why in a minute) of PRI-G additive into 4 liters of gasoline. It’s a lot easier to measure 12.5 mL than 2 mL.

Procedure

Step 1: I labeled each gas can in three locations using a sharpie, pencil and ballpoint pen. It’s overkill, but the last thing I want is to lose track of what fuel is in what container in case I spill gasoline on the outside of a fuel can or the pink fades over time.

Step 2: For my controls, I poured in 4 liters of gasoline into the gas can then closed the cap tightly. No additives were mixed in to either sample.

Step 3: For the samples that had additive added, I poured in 800 mL of fuel, added 15 mL of Sta-bil or PRI-G, then added another 3.2 L of fuel. I then closed the cap tightly, shook the can 10 times, then set it aside. I did this for all 5 samples that had an additive added.

I used 15 mL instead of 12.5 mL because it’s easier to measure, adding extra additive doesn’t hurt anything (per Sta-bil and PRI-G’s website) and I knew a little bit of the additive would be left on the inside of the graduated cylinder, so not all of what I measured in the graduated cylinder would make it in the gas can.

I started with 800 mL, then added the additive, then added the 3.2 L of fuel to assist in the mixing of the additive into the fuel. Besides shaking the gas can 10 times, I wanted added agitation of the fuel and Sta-bil or PRI-G.

Step 4: Placed all 9 samples into the back corner of my garage. This is a fully enclosed portion of the garage, although it’s not air tight. Any changes in temperature and humidity are quickly felt inside the below pictured storage location.

Caption: Storage location of the 9 samples in my garage.

Attribution: Author’s Own Work

Caption: Samples that have been prepared.

Attribution: Author’s Own Work

Future Plans

The samples were created on the evening of May 31, 2018. After at least 1 year, but preferably 2 or 3 years, I will test each sample in a two stroke engine. I don’t know exactly what I will use right now, but I may use my Stihl MS 170. I plan to flush the engine with clean, fresh fuel, then pour in the fuel sample to be tested. I will take both subjective and objective measurements. For example, I will observe how easy they are to start and how many pulls it takes. Then I will measure idle RPMs and wide open throttle RPMs with a tachometer. Exactly how I will measure performance is subject to change. I plan on asking for advice on message boards in the months before I actually perform my tests.

I will also have a record of the temperatures and dew points for the entirety of this test. I plan to get my weather data from www.wunderground.com.