Doc’s Diesel Engine Oils are built to protect hard-working diesel engines. Available in 5W-40, 10W-30, and 15W-40 (Full Synthetic or Semi-Synthetic) Engine Oil, every formula is designed to deliver strong wear protection, lower oil consumption, and rock-solid performance in extreme conditions. Whether you’re hauling, towing, farming, or running a fleet, Doc’s Diesel Engine Oils are made to keep your engine running clean, efficient, and protected. And when it’s time for a change, we’ve got it covered: all oils are available in Oil Change Kits and Oil + Filter Maintenance Kits for hassle-free servicing.
Maximium Engine Protection
Maximized engine protection means your oil isn’t just doing its job, it’s doing it better, longer, and under tougher conditions. Doc’s Diesel Engine Oil is engineered for real diesel work, built to resist thermal breakdown, sludge buildup, and oxidation even when you’re towing heavy, hauling long, or running in extreme heat or cold.
This isn’t your average oil. It’s designed with advanced additives that maintain viscosity and shear stability, keeping your engine’s moving parts protected and clean mile after mile. That means smoother performance, better fuel efficiency, and fewer maintenance headaches.
With Doc’s Diesel Engine Oil, you get longer oil life, stronger protection, and the confidence that your engine can take whatever you throw at it, because when you depend on your truck, you need oil that won’t quit before you do.
Built For Extreme Temperatures
When the temperature drops and the truck has to fire up, Doc’s Diesel Engine Oil doesn’t flinch. It’s built to flow fast in freezing conditions, delivering instant lubrication for smooth, reliable cold starts every time. Even when the frost bites and metal parts contract, your engine gets immediate protection where it counts.
No dry starts. No sluggish performance. Just dependable protection that keeps your rig ready to roll when the job can’t wait. Whether you’re running a Duramax, Powerstroke, or Cummins, Doc’s Diesel Oil is formulated to keep your engine turning strong in the coldest climates.
From early-morning hauls to long winter runs, it gives your diesel the confidence to start, perform, and protect like it should, because downtime isn’t an option when there’s work to be done.
Proven Clean Performance
Oxidation control is what separates average oil from serious engine protection. Doc’s Diesel Engine Oil is formulated with advanced oxidation inhibitors that fight breakdown at high temperatures, keeping your oil stable and your engine cleaner for longer. This means fewer harmful deposits, less sludge, and consistent performance even under heavy loads or long hauls.
By keeping internal components cleaner and better lubricated, your engine runs smoother, cooler, and more efficiently. That translates to less wear, stronger performance, and longer engine life, no matter how many miles you push it.
Doc’s Diesel Engine Oil doesn’t just protect; it preserves power, reliability, and performance mile after mile. Because when your truck works hard, your oil should work even harder.
Engineered for Emissions
Doc’s Diesel Engine Oils meet GHG 17 (Greenhouse Gas 2017) standards, meaning they’re built to protect your engine, your fuel budget, and the environment, all without giving up power or reliability. These oils are engineered to reduce carbon emissions and improve fuel efficiency, helping your diesel run cleaner and smoother mile after mile.
By minimizing friction and optimizing combustion performance, Doc’s Diesel Oils help you get more work done with less fuel waste. You’ll notice cleaner operation, fewer emissions, and a truck that pulls strong while staying compliant with modern emissions standards.
It’s smart protection for hardworking engines, built to meet today’s regulations and tomorrow’s demands, so your truck stays efficient, powerful, and ready for whatever the road throws your way.
Recommended Engine Oil Change Intervals
Regular diesel oil changes keep your engine clean, cool, and properly lubricated. Skipping them leads to buildup, excess wear, and costly repairs down the road.
Standard Service (normal duty): 10,000 – 15,000 miles, or as recommended by OEM
Severe Service (heavy loads, towing, dusty or extreme conditions): 7,500 – 10,000 miles
Off-Road / Agricultural / Equipment: Follow manufacturer guidelines (typically 250 – 500 hours)
👉 Doc’s Pro Tip: Pair your oil with Doc’s Oil Change Kits or Oil + Filter Maintenance Kits for everything you need in one box: filters, seals, and the right amount of oil for your truck.
Oil Properties & Specifications
Every Doc’s Diesel Oil is engineered to meet modern diesel requirements. All four grades share the same high-performance specs, so no matter which one you choose, you’re getting oil that:
Meets or exceeds API CK-4 standards
Supports aftertreatment systems (DPF, SCR, EGR)
Protects against oxidation, sludge, and wear
Provides long-lasting TBN retention for extended drain intervals
SPECIFICATIONS:
Meets or exceeds major specs API CJ-4, SN, and backward compatible with CI-4, CI-4 Plus, CI-4. Cummins CES 20086, DUETZ DQC III-10LA, Mack EOS 4.5, Renault VI RLD-4, Volvo VDS-4.5, ACEA E6/E9, Allison TES-439, Caterpillar ECF-3, Detroit Fluids Specification (DFS) 93K222, MAN M3575, MB 228.51, MB 228.31, MTU Category 3.1
Ready to DIY? Grab Your Oil + Filter Kit Today
Whether you’re running a single pickup, a farm tractor, or an entire fleet, Doc’s Diesel Oils give you the right protection, right viscosity, and right price. Backed by reliable performance and available in complete kits, these oils make it easy to keep your diesel running strong. Ready for your next oil change? Check out Doc’s Heavy Duty Engine Oils and Oil + Filter Kits today.
OIL + FILTER KITS
It's definitely better that anything I've used previously. The engine gets and runs quieter with this in it 🙌
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