Our new fuel test kits are the first and last line of defense in eliminating diesel fuel issues.

Our diesel fuel test kits are the first and last line of defense against costly fuel problems. Never assume your fuel quality is safe. All of our kits are simple to use, low-cost, and designed to help you detect issues before they damage your engine.

If you are outside the USA, contact sales@dieselcraft.com for special export pricing.

Why Diesel Fuel Testing Matters

Stored diesel fuel can quickly develop problems such as water contamination, bacteria growth aka algae, mold, fungus, and even asphaltene buildup. Testing your fuel every 90 days—and testing every new fuel delivery—helps you avoid downtime, repairs, and expensive engine damage.

Our Diesel Fuel Test Kits

Test for: Bacteria / Algae (microbial contamination) in older diesel fuel. If you have plugged filters.
DS-1 Test Kit

Test for: Water contamination in diesel fuel. If you have injector damage.
FCT-100 Water and Fuel Clarity Test Kit

Test for: One Year Old Fuel: Overall fuel clarity, water content, and potential bacteria contamination indicators.
Three in One: FCT-100 Fuel Clarity PLUS DS-1 Bacteria Test

Test for: Contamination caused by accidental DEF exposure in diesel.
Diesel Fuel DEF Test – #DEF-1

Test for: The presence of gasoline in your diesel fuel
GAS-1

Call us for quantity pricing and reseller information: 530-613-2150

Need Help Choosing a Test?

Not sure which diesel fuel test kit you need?
Contact sales@dieselcraft.com and our team will help you identify the correct test for your situation.

If you’re unsure what the problem is, call one of our regional offices:

Fast Shipping – Priority Mail (1–3 Days)

All orders ship via Priority Mail with 1–3 day delivery anywhere in the USA.

Protect Your Engines & Fuel System

Using diesel fuel test kits regularly helps you:

  • Prevent microbial growth
  • Detect water before it causes corrosion
  • Avoid fuel system failures
  • Confirm that delivered fuel meets quality standards
  • Reduce maintenance costs and downtime

Take a closer look at each of our diesel fuel testing kits and safeguard your equipment today.

Frequently Asked Questions

What types of contamination can these kits detect?

Dieselcraft Fuel Test Kits are simple, low-cost diagnostic tools designed to help you detect fuel quality issues such as water contamination, microbial growth (bacteria and algae), gasoline in diesel, and fuel clarity problems before they damage your equipment.

Why should I test my diesel fuel?

Stored diesel can quickly develop problems like water contamination, microbial growth (algae, bacteria, fungus), and reduced clarity. Testing your fuel every 90 days and with every new delivery helps prevent costly engine downtime, fuel system damage, and premature filter failures.

How often should I use a fuel test kit?

Before a new fuel delivery enters your system
Every 90 days for stored fuel
This frequent testing helps you catch contamination issues early and avoid costly repairs or downtime

What types of contamination can these kits detect?

Dieselcraft offers a range of test kits that can detect:
✔ Water contamination in diesel fuel
✔ Microbial contamination (bacteria and algae)
✔ Presence of gasoline in diesel
✔ Fuel clarity and overall fuel condition
✔ DEF (Diesel Exhaust Fluid) contamination in fuel (specific test)

Are these kits easy to use?

Yes. All Dieselcraft kits are designed for simple field use with minimal training. Many tests work with a dip, liquid sample, or indicator strip method so you can get answers quickly without expensive laboratory equipment.

Do the tests give immediate results?

Some tests (like DEF presence tests) can show results in less than a minute.
Microbial contamination tests may take 24–36 hours for results to develop.
Other kits provide immediate pass/fail visual indicators.

What do the results mean?

Pass: No visible signs of contamination and fuel is generally acceptable.
Fail: Contamination detected and fuel may need treatment, polishing, or disposal to avoid damage.

Visual color changes or growth indicators will guide the interpretation depending on the specific kit type.

What should I do if a test shows contamination?

If contamination is detected:
Consider fuel polishing or storage tank maintenance
Use fuel filtration systems
Consult Dieselcraft for fuel maintenance recommendations
Addressing contamination immediately helps prevent engine damage and excessive maintenance costs.