best fuel for fiberglass tank?

stainlesscycle · 02-15-2011, 05:09 PM

both tanks are sealed (caswell), but i'm always paranoid ... i have not had a problem with caswell in fiberglass tanks yet - i have one that's been sealed for 10+ years without a problem - but there's always a first time.

options :

pump gas and drain tanks when not in use/leave cap off. fuel will be in tanks a day or 3 maximum.

or c12 and drain tanks anyways, i just don't gotta be in such a hurry about it. with c12 i'll probably have to rejet.

or avgas? i've never run it.... but supposedly there's a local place here that will let you pump up to 5 gallons into metal container. just walk right up.

c12 = expensive - $10 - $12 gallon, gotta drain it anyways. might get some bonus hp. probably not much.
avgas = cheaper, but i've not used it before
regular old pump gas = cheap, gotta drain it, paranoid about fiberglass....

is there anyone here who regularly uses a proven fuel in their fiberglass tanks?

motomike14 · 02-20-2011, 05:23 PM

I have a caswell sealed tank (used the whole bit of the kit, sealed it twice) and have been using pump 93 gas for well over a year now. Not a single issue.

Caswell customer servie didn't recommend any stabalizer, so when it sits, I drain the tank and the carbs. I would just stick to the high octane pump gas; BP or Shell gas has been friendly to me.

Duck_Pilot · 02-20-2011, 06:50 PM

I'd not recommend avgas. For several years, I used 100 octane low-lead, premixed in my 2T racebikes. It was a mistake. Switching to pump premium unleaded made it run much better, and with less tendency to detonate.

Avgas is a very "dry" burning fuel, without the additives that land-based engines need. As result, it was difficult to jet properly, because the plugs took forever to color. Premixing oil with the 2T motors likely saved them from the additional wear that would have happened in a 4T engine.

I know the question pertained to preserving your fuel tank, and my answer thus far hasn't helped with that. I've run Sinclair premium in my Ducati GT-1000 almost exclusively since new. I've had a touch of fuel tank spreading, but nothing obviously mis-shapen or unsafe about it.

Hope this helps.

Weaverman · 02-21-2011, 03:44 AM

The big problem with fiberglass tanks today is the ethanol in the fuel. Many boats have been forced to undergo fuel tank replacement or be scrapped due to the EPAs allowance of ethanol in our fuel. Over time, ethanol dissolves the resin leaving a leaky, softened, unrepairable mess. The resin in solution has also been known to ruin engines, causing rings and valves to stick, etc.

Not sure of your location, but try this site. It lists fuel stations who sell "neat" gasoline. Hope this helps. http://pure-gas.org/index.jsp?stateprov=PA

Also, I can't comment on how well the various tank sealers resist the effects of ethanol...perhaps a call to the manufacturer of the stuff you used would be helpful.

Luke · 02-21-2011, 08:50 AM

I've let E10 gas sit in a Caswell-lined fiberglass tank for up to two months and it ran fine. The only thing special I did was run the float bowl dry before parking it. This is in a 2T trials bike. Before lining the tank, a freshly cleaned tank and carb with fresh gas would gum up in about 45 minutes of run time.

JLeather · 02-21-2011, 10:11 AM

Caswell is the good stuff, I think you'l be fine. I would definitely drain the tank if it's going to be sitting for more than say a month. Not only should that help with the tank, but this modern crap gas breaks down so fast that I wouldn't want to leave it in there too long anyway.

Don't forget about the fuel lines too. Old rubber doesn't like ethanol any more than fiberglass does.

02-15-2011, 05:09 PM	#1
stainlesscycle ^OP Beastly Adventurer Joined: Jun 2008 Location: morgantown, wv Oddometer: 1,639	best fuel for fiberglass tank? both tanks are sealed (caswell), but i'm always paranoid ... i have not had a problem with caswell in fiberglass tanks yet - i have one that's been sealed for 10+ years without a problem - but there's always a first time. options : pump gas and drain tanks when not in use/leave cap off. fuel will be in tanks a day or 3 maximum. or c12 and drain tanks anyways, i just don't gotta be in such a hurry about it. with c12 i'll probably have to rejet. or avgas? i've never run it.... but supposedly there's a local place here that will let you pump up to 5 gallons into metal container. just walk right up. c12 = expensive - $10 - $12 gallon, gotta drain it anyways. might get some bonus hp. probably not much. avgas = cheaper, but i've not used it before regular old pump gas = cheap, gotta drain it, paranoid about fiberglass.... is there anyone here who regularly uses a proven fuel in their fiberglass tanks? __________________ current bikes 07 gasgas xc300-94 duc 900ss-86 morini camel (2)-84 IT200-83 IT175-78 guzzi lm1-77 pursang 250-76 morini 3 1/2 strada-76 frankentaco pursang 200-74 frankentaco pursang 200-74 morini 3 1/2 sport-74 mz ts250/0-74 puch 175 (3)-73 can-am 175tnt-71 guzzi frankeneldo-71 ossa Stiletto-70 frankentaco sherpa s(2)-66 morini corsarino(2)-63 morini corsaro + many more

02-20-2011, 05:23 PM	#2
motomike14 Thumper Crusader Joined: Jan 2010 Location: Florida Oddometer: 1,020	I have a caswell sealed tank (used the whole bit of the kit, sealed it twice) and have been using pump 93 gas for well over a year now. Not a single issue. Caswell customer servie didn't recommend any stabalizer, so when it sits, I drain the tank and the carbs. I would just stick to the high octane pump gas; BP or Shell gas has been friendly to me. __________________ "Living just to keep going, goin' just to be sane." - The Black Keys I prefer kick starters, air-cooling, and carburetors over anything.

02-20-2011, 06:50 PM	#3
Duck_Pilot Retired Roadracer Joined: Jun 2007 Location: Denver 'Burbs, Colorado, USA. Oddometer: 3,824	I'd not recommend avgas. For several years, I used 100 octane low-lead, premixed in my 2T racebikes. It was a mistake. Switching to pump premium unleaded made it run much better, and with less tendency to detonate. Avgas is a very "dry" burning fuel, without the additives that land-based engines need. As result, it was difficult to jet properly, because the plugs took forever to color. Premixing oil with the 2T motors likely saved them from the additional wear that would have happened in a 4T engine. I know the question pertained to preserving your fuel tank, and my answer thus far hasn't helped with that. I've run Sinclair premium in my Ducati GT-1000 almost exclusively since new. I've had a touch of fuel tank spreading, but nothing obviously mis-shapen or unsafe about it. Hope this helps. __________________ " A man that can have patience, can have what he will." - Benjamin Franklin "Man cannot imagine how life could be more difficult or complex. But Congress can." - Cullen Hightower Honestly, I do like Socialists. They just need a little tartar sauce.

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02-21-2011, 03:44 AM	#4
Weaverman Damaged goods Joined: Jul 2009 Location: Mid-Michigan USA Oddometer: 58	The big problem with fiberglass tanks today is the ethanol in the fuel. Many boats have been forced to undergo fuel tank replacement or be scrapped due to the EPAs allowance of ethanol in our fuel. Over time, ethanol dissolves the resin leaving a leaky, softened, unrepairable mess. The resin in solution has also been known to ruin engines, causing rings and valves to stick, etc. Not sure of your location, but try this site. It lists fuel stations who sell "neat" gasoline. Hope this helps. http://pure-gas.org/index.jsp?stateprov=PA Also, I can't comment on how well the various tank sealers resist the effects of ethanol...perhaps a call to the manufacturer of the stuff you used would be helpful.

02-21-2011, 08:50 AM	#5
Luke GPoET&P Joined: Aug 2004 Location: Idiotville, OR Oddometer: 3,749	I've let E10 gas sit in a Caswell-lined fiberglass tank for up to two months and it ran fine. The only thing special I did was run the float bowl dry before parking it. This is in a 2T trials bike. Before lining the tank, a freshly cleaned tank and carb with fresh gas would gum up in about 45 minutes of run time.

02-21-2011, 10:11 AM	#6
JLeather Bike Butcherer Joined: Aug 2010 Location: Maryland Oddometer: 273	Caswell is the good stuff, I think you'l be fine. I would definitely drain the tank if it's going to be sitting for more than say a month. Not only should that help with the tank, but this modern crap gas breaks down so fast that I wouldn't want to leave it in there too long anyway. Don't forget about the fuel lines too. Old rubber doesn't like ethanol any more than fiberglass does.