I think of this as an adjunct to my book "Keeping a Cruising Book for Peanuts," although certainly there is some overlap. I've tested a lot of stuff. Many of these items were mentioned in some prior post--use the search function to find more information.
While you're at it, subscribe to Practical Sailor Magazine. The product descriptions are better, there are comparisons and options, and the test methods are explained. They research stuff I avoid, like electronics. One good find--or bad purchase avoided--and it'll be the smartest $39.94 you'll ever spend.
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This time I'm going to focus on just one topic, that which lured me into writing in the first place; gasoline and fuel additives, and whether they are snake oil.
11. Gasoline Additives, Corrosion. Ethanol gas (E10) is more corrosive and less stable than non-ethanol gas for two reasons. First, it absorbs water readily from the air and then holds more water in solution. This allows ions to move freely, which facilitates corrosion. Aluminum carburetor bowls are particularly prone to corrosion, and the fluffy corrosion products are very good at clogging jets (it isn't the gum these days). The second is that those metal ions--specifically copper an zinc--are powerful polymerization and oxidation catalysts, accelerating the break down of the gasoline in to gum by over 100 times. The cure? An effective anti-corrosion additive. Biobor EB is my favorite, though Mercury Store-N-Start and Sea Foam are also very good. Walmart is cheap.
As for additives that claim to prevent water absorption or prevent phase separation, they are mostly lying. And even if they could keep the mix together, burning gas with all that water in it is a very bad thing. Avoid these (K100 etc). CRC Phase Guard IV actually made corrosion worse, although I think they may have reformulated since I tested it.
12. Diesel Additives, Corrosion. Corrosion is still important with diesel, and so catalytic decomposition due to copper and zinc. However, Biobor for diesel is strictly a biocide. My recommendation for Diesel is Startron. Need protection from diesel bug too? Startron can be combined with biocides (I tested this combination and many others using proposed ASTM methodology) and the combination provides superior protection.
13. Diesel Additives, Bugs. Gasoline is immune to bacterial and fungal break down--it's too toxic. But diesel can grow a nice crop of snot-like microrganism, cloging filters and secreting acids that accelerate corrosion. The cure is a biocide like Biobor JF or FPPF Kill Em'. By the way, biocides are like the antibiotic your doctor supplies; you need the right one. Biobor is good on one set of strains, and Kill Em' is good on the other, so if Biobor does not work, try the other. However, the dead bugs don't just go away; the bodies must be removed, which mean physically cleaning the tank (pump the fuel out AND scrub the walls). The best answer is prevention through regular treatment, not just storage. Keep it up, even during the summer when you are sailing regularly. You may be using the fuel faster, but the bugs grow faster in the summer too.
About every 3-5 years the silica gel must be regenerated by grilling very low in a pan for 20 minutes. Very easy.
14. Vent Filters. Both corrosion and bugs rely on water. It does NOT have to be a free layer, so it is a semi-myth that fuel/water separators will solve the problem. They reduce water and help remove the solids, but they are NOT a cure, only a treatment. Large amounts of water usually come in through the filler cap--make sure you have a good o-ring and coat it with grease to keep it water repellent. But the insidious source of water--worse for gasoline because it actually sucks the water from the air--is the vent. The cure is a silica gel vent drier. At this time, H2OUT is the only unit on the market, but fortunately, it is very good. Additionally, in the case of gasoline, the vent drier reduces evaporative emissions enough to pay for it over 5 years, so the reliability improvement is all gravy. Saving volitiles also means easier starting. Just all good.
15. Funnels, Siphons, and Spill Prevention. A shaker siphon is the answer. Nearly as fast as pouring, simply place the valve end in the jerry can, push the other end deep into the filler neck, and shake vertically 3-4 times to start the flow. Lift the valve out to stop. No spills, no holding heavy cans. No messy funnels. A clever guy could add a fuel filter for diesel, although it would slow things down. If you prefer to fill at the dock, the Cleanway funnel works well.
The Cleanway funnel give the auto cut-off feature enough buffer to work. Even without auto cut-off, at least it gives you a few seconds. If the vent is lower than the filler, of course, it won't help. Always know how much fuel you need.
I became interested in these topics as a result of chronic engine reliability problems. For the past 8 years I have used Biobor EB and a vent filter, and my problems have simply evaporated. I took my carbs apart a few months ago as part of an article--after 7 years, they looked as clean as new. I was not so much shocked as happy. It's so nice when you turn the key and know it will start, even in the winter.