Monday, January 21, 2013

Corrosion Protection and Diesel Additives--Which Ones to Test?

rev. 1-28-2013

I've tested gasoline additives regarding phase separation: good fuel management and vent filters work, additives don't. I've tested gasoline additives for corrosion protection; many were very good, some incredible, some useless, and one even made things worse. I've tested the effect of vent filters on gasoline corrosion; they help.

I've tested diesel biocides; most work well. I've started a diesel fuel test for corrosion, with and without a silica gel vent filter. In 3 months we'll know something.

I've always been more interested in gasoline because my boat runs on gasoline; I've neglected diesel and a few friends have reported tanks corroded through, some from the inside, some from the outside. Time to set that straight. I will be starting starting a set of corrosion tests based upon ASTM procedures but with a few modifications developed during our gasoline testing experience.
  • 1-liter jars 50% full with 10-inch x 1/8-inch vent lines to allow controlled breathing.
  • A trace of seawater (0.02%).  About 2 drops. The coupons will be elevated above the bottom and not in contact with any precipitated water.
  • Vinegar. testing of separator samples and research suggest acetate and low pH are common. About 25% vinegar in water. pH about 4.
  • The recommended dose of treatment.
  • Ambient summer temperatures.
  • Standard ASTM corrosion coupon packs, but arranged to allow galvanic couplings of key metals. Most probably brass/steel copper and steel/aluminum/brass. Serious corrosion is generally the result of galvanic action.
Our gasoline experiences suggest that the right additive should stop internal corrosion cold. However, remember that more is NOT better; some of these additives can cause carb or fuel rail issues if over concentrated, and their function is not generally improved with increasing dosage. Our testing at varying doses suggest the chemistry is either right or it's not. This is generally true with most corrosion protection systems, including engine coolants and lubricants, where I have long expereince.
So what should we test? I'm thinking...
  • Stabil Fuel Stibilizer
  • Sea Foam
  • Standyne Performance Formula

Added based upon comments, below and e-mail...
  • Biobor JF. After all, Biobor EB was probably the best gasoline treatment.
  • Star Tron. 
  • ValveTech Bioguard
  • Fuel Right

Any favorites?


  1. Not strictly a corrosion inhibitor, but it supposedly prevents microbes which cause corrosion... how about Biobor JF? It's the only thing we put in our tanks except #2 diesel.

    s/v Eolian

  2. Drew, FWIW, I use Star brite Star*Tron Diesel Additive in my Yanmar 2GM20F. It was recommended by the Yanmar authorized dealer in town. From the product description...It uses enzymes to modify how diesel fuel burns, the end result being more complete and uniform combustion. Dispenses bacteria, cleans the fuel delivery system and combustion chambers, stabilizes fuel chemistry, reduces engine emissions, increases power, cleans injectors and improves fuel economy. 8oz treats 256 gallons. Cost is $10-$15 per bottle. I bought a bottle three years ago and haven't used half of it yet! Ahhhh, the joy of sailing!