Fiberglass Tanks and Gasoline Additives

Fritz · Sep 11, 2008

As a follow up to my thread regarding my leaking fiberglass tank, which I plant to re-Caswell this weekend, I'm wondering if there are any opinions out there regarding additives in various gasoline brands...and their effects on our old tanks.

As I understand it, the main culprit is ethanol. Here in Florida, it's a state law that ALL gasoline brands must contain a minimum 10% ethanol...so I can't get away from that particular additive. What I'm wondering about is the other additives like the Techron in Chevron etc. that might be contributing to the fiberglass breakdown or rendering our Caswell treatments as "temporary cures". I've always trusted "top-tier" gasoline brands like Shell, Chevron, Mobil, Exxon, etc. but they all advertise additional additives that I'm worried might be contributing to the effects of the ethanol. Just wondering if there are any opinions on this subject.

mikegray660 · Sep 11, 2008

Fritz said:
As a follow up to my thread regarding my leaking fiberglass tank, which I plant to re-Caswell this weekend, I'm wondering if there are any opinions out there regarding additives in various gasoline brands...and their effects on our old tanks.

As I understand it, the main culprit is ethanol. Here in Florida, it's a state law that ALL gasoline brands must contain a minimum 10% ethanol...so I can't get away from that particular additive. What I'm wondering about is the other additives like the Techron in Chevron etc. that might be contributing to the fiberglass breakdown or rendering our Caswell treatments as "temporary cures". I've always trusted "top-tier" gasoline brands like Shell, Chevron, Mobil, Exxon, etc. but they all advertise additional additives that I'm worried might be contributing to the effects of the ethanol. Just wondering if there are any opinions on this subject.

buy an alloy tank :wink:

Ron L · Sep 12, 2008

buy an alloy tank

From the National Marine Manufacturers Association:

"In the case of aluminum tanks, aluminum is a highly conductive metal that relies on an oxide layer for its corrosion protection properties. Low levels of ethanol, such as E10 (10%), are usually not a problem in aluminum tanks because the oxide layer provides a good measure of protection. The problem occurs when the ethanol content is increased.

There are two mechanisms that occur with ethanol. Both mechanisms are a result of the hydroscopic property of ethanol, meaning it absorbs water. The more ethanol in the fuel, the more water there will be in the fuel tank. Water not only causes the tank to corrode, it also causes the corrosion particles to clog fuel filters, fuel systems, and damage engine components. The corrosion rate can be accelerated under a number of conditions if other contaminating metals are present such as copper which may be picked up from brass fittings or as a low level contaminant in the aluminum alloy. Chloride, which is a chemical found in salt water, will also accelerate corrosion. In the long term, corrosion can perforate the aluminum to produce leaks that would cause fuel to spill into the bilge and end up in the environment. In the worse case it could cause a fire and/or explosion hazard. Boat fuel tanks are often located under the deck next to the engine where the operator might not be aware of a leak until it was too late. .

The second mechanism that can occurs with the increased use of ethanol based fuel in aluminum tanks is galvanic corrosion. Gasoline fuel is not conductive, but the presence of ethanol or ethanol and water will conduct electricity. The galvanic process that occurs to aluminum trim tabs, stern drives, shaft couplings, etc. will occur within the aluminum fuel tank. Boat builders are able to protect exterior aluminum boat equipment with sacrificial anodes known as zincs. Sacrificial anodes are not a feasible option for the interior of a fuel tank."

mikie3117 · Sep 12, 2008

Hello to all. I had the same type of issues and bought a Norvil fastback tank. Aluminum seemed to be the only, albeit expensive option. There is a very pretty one on E-Bay now.
I also spent a lot of time working in the maritime industry i.e. Navy. We used special paints to build the oxide layer mentioned. I am pretty aware of what is going on inside my fuel system and am not concerned about corrosion. I have been running this system in Colorado with ethanol for over two years with no issue. If I see any issues I will bring it up.
Mike

aceaceca · Sep 12, 2008

If you do a Google search with the words fiberglass and gasoline you will find some really good articles of actual testing that has been done on this matter. Tests were initiated by boaters with fiberglass tanks. I think the best advise is to switch to an aluminum or steel tank. I know my fiberglass tank is being consumed by my engine. Sometimes it gets little blisters and sometimes it gets a little soft. I know at one time I put some octane booster in it and it really didn't like that. I do not trust the coating being sold due to past stories on cars where the stuff just disappeared over time. With the cost of just a tank for a Norton approaching $6 to 7 hundred dollars before you are done, you might as well just buy another bike with a steel tank.

mikegray660 · Sep 12, 2008

Ron L said:
buy an alloy tank

Click to expand...

From the National Marine Manufacturers Association:

"In the case of aluminum tanks, aluminum is a highly conductive metal that relies on an oxide layer for its corrosion protection properties. Low levels of ethanol, such as E10 (10%), are usually not a problem in aluminum tanks because the oxide layer provides a good measure of protection. The problem occurs when the ethanol content is increased.

There are two mechanisms that occur with ethanol. Both mechanisms are a result of the hydroscopic property of ethanol, meaning it absorbs water. The more ethanol in the fuel, the more water there will be in the fuel tank. Water not only causes the tank to corrode, it also causes the corrosion particles to clog fuel filters, fuel systems, and damage engine components. The corrosion rate can be accelerated under a number of conditions if other contaminating metals are present such as copper which may be picked up from brass fittings or as a low level contaminant in the aluminum alloy. Chloride, which is a chemical found in salt water, will also accelerate corrosion. In the long term, corrosion can perforate the aluminum to produce leaks that would cause fuel to spill into the bilge and end up in the environment. In the worse case it could cause a fire and/or explosion hazard. Boat fuel tanks are often located under the deck next to the engine where the operator might not be aware of a leak until it was too late. .

The second mechanism that can occurs with the increased use of ethanol based fuel in aluminum tanks is galvanic corrosion. Gasoline fuel is not conductive, but the presence of ethanol or ethanol and water will conduct electricity. The galvanic process that occurs to aluminum trim tabs, stern drives, shaft couplings, etc. will occur within the aluminum fuel tank. Boat builders are able to protect exterior aluminum boat equipment with sacrificial anodes known as zincs. Sacrificial anodes are not a feasible option for the interior of a fuel tank."

Ron
your post is to long to read, but i take it that your norton's a boat? :lol:

BillT · Sep 12, 2008

I also am a Florida resident, and my fiberglass tank lasted about a day and a half before the Caswell lining started to peel. The stuff came out in rubbery flakes which hardened back up once allowed to dry. Caswell said they were sending me a stronger mix, but I still haven't seen it.

I got one of those Pakistani tanks from Old Britts. The tank wasn't perfect, and I had to JB Weld around the filler neck (pinhole leak that didn't show itself until AFTER I painted the tank), but I'm not worried about the thing melting between my knees. I could swear this metal tank holds about 3 1/2 gallons, too.

Ron L · Sep 13, 2008

your post is to long to read, but i take it that your norton's a boat?

Only when it rains!! :lol:

debby · Sep 13, 2008

I just filled up with ethanol-free Premium today. Bike seems to be running better, although that could just be my imagination.

It turns out the local regulations only require ethanol in our fuel from November through April, but most stations sell the stuff year-round because it's more profitable. :evil: I found out about a station still selling the good stuff, so I got some today. I guess I'll be buying all of my motorcycle gas there now, at least until November.

Three seasons on my Caswell-lined fiberglass tank now, and no issues. I've heard the fuel formulas are different in the east though.

Debby

zotz · Sep 14, 2008

I've had this stuff in my tank for the last 5 or 6 years with no problems. It's specifically alchohol resistant.

http://www.hirschauto.com/products.asp?dept=4

mikegray660 · Sep 14, 2008

debby said:
I just filled up with ethanol-free Premium today. Bike seems to be running better, although that could just be my imagination.

Debby

ethanol free gas... damn i'm jealous

debby · Sep 14, 2008

Don't be too jealous. I only know of one station that still sells it, and I think their days are numbered. I read something about a "new gasoline formula" being approved for our area due to Denver's too-high ozone levels. That can't be good news for vintage motorcyclists.

Debby

Fiberglass Tanks and Gasoline Additives

Similar threads