Pri-D for Diesel Storage?

Star Tron + Biobor still best overall diesel treatment.


In your November 2015 article on the best overall gasoline and diesel treatments for storage, you gave recommendations for treating diesel fuel tanks. After reading your article, I am inclined to buy Star Tron Diesel ( and add it with the Biobor JF ( that I already have on hand. But I also have a product made by Power Research Inc. (, Pri-D Complete Diesel Treatment, which I got when I had my fuel tanks cleaned at a boatyard. On the Pri-D label, it claims to be a stabilizer, cuts smoke, removes algae and slime, lubricity for ULSD. This was not one of the products PS evaluated. Are you aware of it? Is it any good?

Clifford Kurz

Voyager, Tashiba 40

Jamestown, R.I.

Although we have not yet tested the Pri-D concentrated diesel treatment, we plan to include it when we revisit fuel additives in the near future. We have had a handful of readers report great success using the Pri-D. Pri-Ds sister product, Pri-G, which is a concentrated gasoline treatment, was included in the November 2015 report. We refrained from giving it an overall recommendation as a storage additive because it was not a top performer in our earlier phase-separation test (see PS, November 2008 online) or corrosion test (see PS, November 2012 online).

As far as combining fuel additives, the Star Tron + Biobor JF mixture is the only one weve actually tested. In the 2015 evaluation, the combo was the top overall performer for protecting stored diesel. Star Tron and Biobor each serve different functions: Star Tron was a top pick in anticorrosion tests and anti-aging tests, and it provides complimentary anti-bug activity to the Biobor. The combination is recommended for all-around protection.

Remote Oil Filters

Regarding the relocated engine-oil filter setup in the February 2015 issue, what are the parameters for doing this without causing possible damage to the engine? How many angles / elbows can the oil lines make including where they enter the adapters on each end? How much higher should one go than the existing location in the engine, and what should the maximum length of the extension hoses be? Doing this would help in many boats (such as mine), where the space around the engine is tight and the access to the oil filter is fair or poor, but on the other hand, one does not want to risk damaging the engine, if such a risk exists.

Ken Simpson


Check with your engine maker before installing a remote oil filter, especially if you intend to mount the filter in a location that is far from the engine, or involves elbows and long hose runs. As there are a lot of variables between different engines, the manufacturer would be the best source to ask specific questions like the number of elbows, maximum hose length, etc.

With commonsense, forethought and care, especially during oil changes, the possibility of damaging the oil system with a remote filter is slight. The types of pumps used in oil systems are generally not prone to losing pressure, even if some air enters the system. However, we have come across remote oil systems that did not come up to pressure after oil changes.

Generally speaking, you would have to mount the remote filter quite high to cause a noticeable drop in pressure. A simple preventative measure is to ensure your oil-pressure alarm system and pressure gauge are working, and to check your oil pressure immediately after an oil change. One bad fitting can cause all the oil to end up in the bilge, and without a low oil-pressure cutoff or a loud alarm, the engine comes to a final stop.

Often, mounting the remote filter in a lower location solves the problem. You can also fill the new filter with oil before spinning it onto its mount. Some engine-lubrication oil circulation pumps seem more willing than others to put up with a greater pressure head caused by how high above the oil level in the pan the filter is located.

The bottom line is to make sure that the oil pressure quickly rises to normal once you start the engine after an oil/filter change, and follow the engine makers guidance about remote mounts.

Practical Sailor has been independently testing and reporting on marine products for serious sailors for more than 45 years. Supported entirely by subscribers, Practical Sailor accepts no advertising or any form of compensation from manufacturers whose products we test. Testing is carried out by a team of experts from a wide range of fields including marine electronics, marine safety, marine surveying, sailboat rigging, sailmaking, engineering, ocean sailing, sailboat racing, and sailboat construction and design. This diversity of expertise allows us to carry out in-depth, objective evaluation of virtually every product available to serious sailors. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser with more than three decades of experience as a marine writer, photographer, boat captain, and product tester. Before taking on the editor’s position at Practical Sailor, Darrell was the editor of Offshore magazine, a boating-lifestyle magazine serving the New England area. Darrell has won multiple awards from Boating Writer’s International, including the Monk Farnham award for editorial excellence. He holds a U.S. Coast Guard 100-ton Master license and has worked as a harbor pilot and skippered a variety of commercial charter boats.


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