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Discussion Starter · #1 · (Edited)
Will low sulfur diesel or low aromatics diesel cause fuel system leaks?


The introduction of low sulfur diesel for on-road use in the U.S. was accompanied by fuel system leaks in a very small percentage of vehicles. Investigations into the cause of these leaks suggest that the problem was linked to the change in the aromatics content of the fuel and to seal material and age.
Diesel fuel systems contain "O-rings" and other parts made of elastomeric materials. These elastomers swell slightly when they contact diesel fuel, because they absorb aromatic compounds from the fuel. Exposure to a fuel with a lower aromatics content will result in some of the absorbed aromatics being leached out, causing the elastomer to shrink towards its original size. If the elastomer is still pliable, this shrinkage will not cause a leak. However, if age or service at higher-than-normal temperatures has caused the elastomer to loose its elasticity, a leak could occur. Vehicle owners should be aware that elastomeric parts have finite lives and should be replaced as necessary.

By itself, low sulfur or low aromatics diesel fuel does not cause fuel system leaks. They are caused by the combination of a change from higher to lower aromatics fuel and aged O-rings and elastomeric parts that have lost their elasticity.​


My experience with O-rings where they can absorb aromatic compounds is when you replace them go with EPDM, KALREZ or VITON........we deal with this at work every day

Cheers,Kevin
 

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I've heard, but can't say from personal experience, that using Biodiesel, even as low as B5, can counteract the issues with the new ULS WRT seal shrink and lubricity.
 

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Discussion Starter · #3 ·
B5 is excellent for lubricity replacment on ULSD

I would buy it year round if I could find it
 
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