New wing tanks

[Maverick]

I am building a series 5 kit manufactured in 1994. The original tanks look fine but, because I haven't yet installed the tanks, I have ordered new ones. Because of the recent article about what fuel to use in a Rotax engine showing advantages and disadvantages of 100LL versus auto-fuel, I figure that with the newer tanks, it won't matter what I finally end up using. (see article in August 2019 Sport Aviation, page 120).

[jiott]

This is just an opinion, but I have a hunch that Kitfox Factory (and also Stick & Rudder) recommend 100LL because of the typical legal liability issue. They both deal with the general public and by going with the standard 100LL they eliminate any liability that MIGHT occur if someone has a serious problem with a bad batch of Mogas. No one is going to have a sudden engine failure due to 100LL, its more of a long term engine life issue. Each of us must weigh the issues and make our own decisions-end of my 2 cents worth.

[KitfoxSS]

Kitfox markets the tanks as being Ethanol "Resistant".
This is ethanol resistant, not ethanol proof.
If it was ethanol proof that would mean the fiberglass tanks would take ethanol all day everyday into the future for the life of the tanks with out issue.
This is not the case as ethanol is some corrosive stuff. The fiberglass tanks are treated to be resistant to ethanol. Meaning you can run it and it'll be ok but continued use over a long period of time and the ethanol will eventually start to effect the fiberglass.

[Vande17941]

How about using a sealer on the fiberglass tanks such as BILL Hirsch Fuel Tank sealer? It's supposed to he resistant to all the additives and ethanol.

I'm in Calif....no ethanol free gas here

[jmodguy]

How about using a sealer on the fiberglass tanks such as BILL Hirsch Fuel Tank sealer? It's supposed to he resistant to all the additives and ethanol.

I'm in Calif....no ethanol free gas here

Skystar lined their tanks with Kreem. It was not optimal. Newer resins that are more resistant are being used now. S&R uses 100LL with decalin and Paul told me it works just fine.

[KitfoxSS]

How about using a sealer on the fiberglass tanks such as BILL Hirsch Fuel Tank sealer? It's supposed to he resistant to all the additives and ethanol.

I'm in Calif....no ethanol free gas here

You can, in fact I had planned when I eventually get to building to use Caswell's Tank sealer. It's a two part epoxy instead of a one part like Kreem or Por15.
From everything I've read it's highly rated.

[HighWing]

I've been reading this and have a few thoughts. My first Model IV started flying in 1998 and I used mogas except on cross countries for nine years. California mandated all mogas have 10% ethanol in 2004. The original tanks were kreemed, and I re-Kreemed one tank bacause of some discoloration on the fabric below the tank. I then flew until late 2007 - three years with ethanol containing mogas primarily. My new Model IV has the Denney Aerocraft tanks with Kreem. I am using 100LL primarily because my flying is spotty and I have had serious issues with the mogas in infrequently used garden equipment and didn't want the same type issues in my Kitfox. I do use Decalin with the 100 LL. Then an article in the last issue of Sport Aviatrion - page 120 - talks about the pros and cons of mogas vs. avgas and in the article it mentions that the new Shell - Sport plus 4 has additives that keeps the tetra ethyl lead in suspension. It makes me wonder if the additive Shell uses would preclude the need for the Decalin. In other words, since Shell is adding an additive to the recommended oil that essentially does the same thing as the Decalin additive - is Decalin use still necessary.

[markwalker]

Thanks for the information!!!! I will do my due diligence with the tank inspection and plan to use 91 octane ethanol free unleaded for regular use and 100 LL when on trips if ethanol free is unavailable.

[jiott]

I would recommend calling the factory to find out when they started supplying the new tanks in the kits. If yours are the old ones, I personally would change them out to the new ones. Fuel system worries are one thing I don't want to have-its too critical. Just my 2 cents.

[markwalker]

I recently purchased an early 1990's kitfox 4 that has a little flaking around the tank necks. Will This continue if I only use only
non-ethanol or 100 low lead or is it too late and the tanks need to be resealed or replaced?