the best fuel filter for gasoline engines

ALL gasoline intended for use in automobiles in the US MUST contain 10% ethanol, including here in FL. But the marinas succeeded in getting an exemption from this requirement, so you can get ethanol-free gas, including the *original* Amoco ultimate at your local marinas.

100LL runs fine in 4-stroke engines, but is no good for 2-strokes. Remember that while the 'LL' in 100LL (blue) stands for 'Low Lead', this 'low' is only in comparison to the older '100' (green) grade of avgas. 100LL actually contains an enormous amount of lead (as TEL) at 2 grams/gallon, about twice the amount that street gasoline EVER had, so it's really not good for long term use in a two-stroke engine, and certainly not a 'low lead' formulation by street gas standards.

Back when all street gasoline had lead in it, there was this special gasoline we used to call "Amoco White Gas" which, while a high octane rated fuel, contained NO lead at all. This was the recommenced fuel for two-stroke outboard engines, since lead will foul spark plugs and leave lead deposits on the piston crowns on two-strokes. The only problem with the stuff was that you could only buy it at a marina, and you had to pay about 25 cents extra per gallon over street premium grade. Nevertheless, I used to make special trips to a local marina to get 'Amoco white gas' for my Maico dirt bikes.

For the longest time, a marina was the only place you could buy the stuff. Then in the early 80's it began to show up at Amoco gas stations under the name "Amoco Ultimate" in anticipation of the phase-out of lead in US street gas in 1985. Now that formulation has basically disappeared again, except at some marinas.


Jimbo

 

We do have a gas station on Plantation Key that advertizes no ethanol (i think 90 octane) gas. The station is owned by a fuel distributor here.

 

Ok, I talked to Mercury Marine about putting filters between my outboard engines and my fuel tanks - their answer was "don't do it". She explained that my 2008 Optimax 225s have fuel filter/water seperators built onto the engines. An additional filter will cause a restriction and the engine won't be able to suck gas thru the additional filter.

After talking to the Mercury factory, I talked to my local shop - very highly regarded shop - the owner told me that Mercury used to recommend not putting filters in, but they started recommending them because of ethanol - that boats need the extra water separator capacity. Also, if the filter clogs or gets filled with water while at sea, pulling the cowlings off the engines and climbing out to fiddle with the filters on the engine is a p.i.a. - so filters inside the boat are the way to go - but apparently they need to be clean enough to not cause too much restriction.

 

Jimbo

Whats the problem of the 100LL in outboards?

Cheers
Powerabout

 

As Jimbo said above, it leaves lead deposits on the piston and on the spark plug, which interferes with proper combustion, which causes your motor to run really bad.

 

Weve had E85 and B5 biodeisel in Thailand for years, you just getting it?

It makes no difference,- we went through all this crap "oh my Ferrari wont run on this stuff" its ok .

Its the 2 strokes that went on it first. I don't care any more what I use in what ever vehicle, I cant tell the difference, in fact I search for Bio.

 

So what happens to all the guys racing outboards and using 100LL or 100 as cheap high octane supply?
There are some other sites with big long threads the pro's and cons of avgas but they never mention a lead problem?
hence my question?
maybe only long term problems with twice as much lead or low speed fouling? dunno

 

The answer is in your own post; there's no such thing as "Long Term" racing use! A boat owner wants to get 5 or 10 years of untroubled service from his engine. A real race engine comes apart no less than once a season, sometimes more often; sometimes MUCH more often

Jimbo

 

fair enough

 

The answer is in your own post;

LL stands for LOW LEAD ,

its not the avgas your grand daddy flew with ,

FF

 

it still has to work with those same WWII engine though ya?
Is that why they have 100LL and the 100/130 now called 100

 

Fred.

It's only a 'low lead ' formulation compared to other aviation fuels, NOT compared to street or boat gas. 100LL has a LOT of lead when compared to street gas.

Jimbo