Heavy-duty diesel engine bay lit in amber light

Additives with attitude

Protect the metal.
Keep the power.

Diesel-grade lubricants and additives built for trucks that work — cold starts, heavy tow, long idle and fleet intervals. Made for mechanics, sold to anyone who'd rather not do the job twice.

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3
Proven formulas
1:6
ProMax treat ratio
5 yr
Shelf life
Made in North America
Lab & field tested
Trusted by diesel shops
Fleet & bulk ready
4.9 / 5 — 412 reviews

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Three formulas. No filler.

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ProMax Performance Oil Additive

Metal-bonding oil treatment

ProMax Performance Oil Additive

ProMax soaks into metal.

  • Cuts friction and operating heat
  • Guards against cold-start wear
  • Engines, gearboxes and diffs
From $29.95

In stock — ships same day

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Free shipping over $99 · 30-day returns · Secure checkout

Diesel Fuel Lubricant (DFL)

Fuel system & injector protection

Diesel Fuel Lubricant (DFL)

Anti-wear protection, every tank.

  • Cleans injectors and fuel systems
  • Restores lubricity to modern ULSD
  • Bulk pails for fleets & shops
From $24.95

In stock — pail sizes available

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Free shipping over $99 · 30-day returns · Secure checkout

Katz Azz Brake Blaster brake and parts cleaner aerosol can

Coming soon

Brake Blaster & Parts Cleaner

High-pressure brake and parts cleaner. Fast-flash, residue-free. Join the list to get first pallet access.

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Why Katz Azz

Additives earn their place or they don't go in.

Every Katz Azz formula has a specific job: reduce friction, protect metal, improve lubricity or keep fuel systems working cleanly under real operating conditions.

Penetrates metal

Formulas designed to work into microscopic surface imperfections so protection stays where the load is.

Reduces friction

Less metal-on-metal contact means less heat, less wear and smoother operation under demanding loads.

Protects fuel systems

Restores lubricity and helps protect pumps and injectors from the wear associated with modern low-sulfur diesel.

Built for duty cycles

Cold starts, long idle, heavy tow and fleet intervals — the conditions working trucks actually see.

Product deep dive

Real jobs. Real results.

Katz Azz Super Lube penetrating lubricant aerosol can

Use case — seized hardware

Rusted solid for 11 years. Free in 90 seconds.

A leaf-spring U-bolt on a '99 3/4-ton had been salted every winter since it left the factory. Two soaks of Super Lube, one breaker bar, no torch, no snapped stud, no drilling out a fastener at 2am.

Before

Before: hardware fused, penetrant beading on top of the rust

After

After: threads wet, fastener turning by hand

Add Super Lube — $14.95 Technical info
ProMax Performance Oil Additive 4 litre jug

Use case — high-mile engines

The first 30 seconds cost you the most wear.

Cold starts happen before oil pressure does. ProMax stays bonded to the metal after shutdown, so the bearings, cam and cylinder walls are already protected on the crank — and it keeps working between service intervals.

Before

Before: dry-metal contact and clatter on start-up

After

After: quieter start, lower oil temp under tow

Add ProMax — $29.95 Technical info
Diesel Fuel Lubricant (DFL) 4 litre jug

Use case — injectors & pumps

An injector set costs more than a decade of DFL.

Deposits and low-lubricity fuel wreck spray pattern first, then the pump. Dose every fill: DFL cleans the tips, restores lubricity to the pump, and keeps power and fuel economy where they were the day you bought the truck.

Before

Before: hazy spray pattern, hard starts, rough idle

After

After: clean pattern, smoother idle, restored economy

Add DFL — $24.95 Technical info

Shop talk

What shops and drivers say

We keep Super Lube on every bay cart. It's the only penetrant my techs stop arguing about — U-bolts, exhaust clamps, brake hardware, it just works.
Dale R. Shop foreman, heavy-duty repair — Alberta Verified buyer
Ran ProMax in a 6.7 at 410,000 km. Oil temps down under tow, and the top-end noise on a cold morning is basically gone.
Marcus T. Owner-operator, 2 trucks Verified buyer
DFL goes in every fill across our fleet of nine. Injector replacements dropped off a cliff and the drivers noticed the throttle response first.
Janelle K. Fleet maintenance manager Verified buyer
I sell a lot of additives. This is the one I actually run in my own truck, and I tell customers that.
ProTech Diesel Center Authorized reseller Verified buyer

Where to buy

Also stocked by authorized diesel dealers

ProTech Diesel Center DieselR Corp Northline Truck Parts Cache Valley Diesel
Find a dealer near you

Technical info

Dosage, compatibility & bulk

Still unsure what your application needs? Our team runs the same products in their own trucks.

Ask a technician

One bottle treats up to 6 litres of oil. Add it with every oil change — pour it in before the fresh oil so it distributes as the engine comes up to pressure. Gearboxes and differentials use the same 1:6 ratio.

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