If you drive a diesel vehicle, you’ve likely heard about Diesel Exhaust Fluid—or DEF for short. It’s a key part of your emissions system, and keeping it topped off is essential for your engine’s performance and compliance with emissions standards. At Grease Monkey®, we make it quick and easy to refill your DEF and keep your diesel running clean.
What Is Diesel Exhaust Fluid (DEF)?
DEF is a non-toxic fluid made of urea and deionized water. It’s injected into your diesel vehicle’s exhaust system to break down harmful nitrogen oxide (NOx) emissions into harmless nitrogen and water vapor. Basically, it helps your diesel burn cleaner—and that’s better for both your engine and the environment.
What We Do
Our DEF service is fast, simple, and done while you wait. Here’s what our Grease Monkey technicians take care of:
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Check your DEF level
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Top off or refill with high-quality DEF that meets EPA standards
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Inspect for any DEF system alerts or warning lights
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Reset any applicable dashboard alerts (where possible)
You’re in and out in just a few minutes—and back on the road with peace of mind.
Why Is DEF Important?
Modern diesel engines rely on DEF to run properly. If your DEF tank runs dry, your vehicle could enter limp mode or even fail to start. Keeping DEF filled:
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Helps your vehicle pass emissions tests
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Prevents performance issues and dashboard warnings
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Keeps your diesel compliant with federal regulations
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Protects engine components tied to the emissions system
It’s a small service that keeps everything running right.
How Often Do You Need to Refill DEF?
That depends on how and where you drive. Most diesel vehicles use 1–3 gallons of DEF every 800–1,200 miles, but heavy-duty or towing applications might use more. If your vehicle has a DEF gauge or low-fluid alert, don’t ignore it—come see us when it gets low.
Signs You Might Need DEF Service
Not sure when to stop by? Keep an eye out for:
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Low DEF warning light
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Limp mode or engine performance issues
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Failed emissions test
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DEF system alerts on your dashboard
If you’re getting any of those signals, we’ll take care of it—fast.
Why Choose Grease Monkey for DEF Service?
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Quick service for diesel drivers
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Clean, EPA-compliant DEF fluid
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Experienced technicians who know diesel systems
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No appointment needed—just drive in
Whether you’re towing, hauling, or commuting, our team makes sure your DEF levels are good to go.
Don’t let something small keep your diesel from performing big. Stop by Grease Monkey® for a fast and easy Diesel Exhaust Fluid service today.
Find your nearest location and keep your DEF topped off!
Only available at participating locations.
