Diesel Fuel: How To Stop Engine Killing Crud

Updated Aug 13, 2015

water in diesel in beaker


Clearing up concerns about diesel fuel contamination; how to stop the crud


By Steve Temple

Keeping diesel pickups running reliably starts with the three Cs: clean air, clean oil and clean fuel.

As durable and powerful as today’s diesel pickup engines are, their Achille’s heel is the fuel: If it’s “off spec,” there’s gong to be a hefty price to pay.

SAE studies indicated that as much as 70 percent of filling-station diesel doesn’t meet design standards of OE engine manufacturers, especially in the area of lubricity.

One distributor we contacted (who asked to remain anonymous), sees variances in fuel quality as often as once a month. These variances can be caused by different sources of crude, types of refining processes, seasonal changes in formulations – and how the fuel is stored.

Water in fuel leads to major internal problems starting with broken injector tips.Water in fuel leads to major internal problems starting with broken injector tips.

How can you determine if your fuel is contaminated?

A visual inspection will reveal a lot, showing discoloration, cloudiness, or separation of liquids and particulates. Of course, a plugged filter is also a good indicator there’s a big fuel problem.

It’s also good to have your diesel fuel tested from time-to-time to make sure you are getting what you pay for whether it’s from a wholesaler or Big John’s Deli & Gas up the street.

Here’re hot links to various labs around the country that test diesel and gas for contaminants and meeting ASTM specs:

Whatever the symptoms of fuel contamination, they should not be ignored.

Bad diesel fuel will invariably lead to serious [costly] damage to both the truck’s fuel system and engine. Small fuel contamination issues escalate very quickly to major problems. –Pro