Doc's Diesel

5W-40 Full Synthetic Heavy-Duty Diesel Oil

$42.99
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Doc's Diesel 5W-40 Full Synthetic Heavy-Duty Diesel Oil

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VEHICLE FITMENT
INTERCHANGE

HEAVY DUTY DIESEL ENGINE OIL

Innovative Protection

Innovative Protection

All-Weather Performance

All-Weather Performance

Extreme Load Stability

Extreme Load Stability

Emissions-Ready & Efficient

Emissions-Ready & Efficient

Innovative Protection

Built for durability, this oil fights sludge and deposits with strong oxidation and thermal stability.

All-Weather Performance

Cold-start ready with fast-flowing protection in ultra-low temps when your engine needs it most.

Extreme Load Stability

Stay-in-grade formula resists thinning under heat and heavy loads for consistent component protection.

WHAT OIL IS BEST FOR YOUR TRUCK?

15W-40 FULL SYNTHETIC

The classic heavy-duty diesel oil—tough, proven, reliable. Excellent for hot climates, towing, and high-load conditions. Fits most Cummins, Powerstroke, and Duramax setups with no issues.

5W-40 FULL SYNTHETIC

Best for cold climates since it flows better at startup. Go-to pick for modern turbo diesels like Duramax, Powerstroke, and Cummins. Approved by many OEMs for year-round use where cold starts are common.

10W-30 FULL SYNTHETIC

Provides slightly better fuel economy due to lower viscosity. Recommended by Cummins for some medium-duty trucks. Works best in moderate climates, but may not protect as well in high-heat/heavy towing compared to 15W-40.

15W-40 SEMI-SYNTHETIC

Budget-friendly option that still gets the job done. Offers less extreme temperature performance than full synthetic. Great for fleet trucks or regular oil change intervals.

WHAT OIL IS BEST FOR YOUR TRUCK?

15W-40 FULL SYNTHETIC

The classic heavy-duty diesel oil—tough, proven, reliable. Excellent for hot climates, towing, and high-load conditions. Fits most Cummins, Powerstroke, and Duramax setups with no issues.

5W-40 FULL SYNTHETIC

Best for cold climates since it flows better at startup. Go-to pick for modern turbo diesels like Duramax, Powerstroke, and Cummins. Approved by many OEMs for year-round use where cold starts are common.

10W-30 FULL SYNTHETIC

Provides slightly better fuel economy due to lower viscosity. Recommended by Cummins for some medium-duty trucks. Works best in moderate climates, but may not protect as well in high-heat/heavy towing compared to 15W-40.

15W-40 SEMI-SYNTHETIC

Budget-friendly option that still gets the job done. Offers less extreme temperature performance than full synthetic. Great for fleet trucks or regular oil change intervals.

What Your Diesel Deserves

Doc’s Diesel Oils are built to protect hard-working diesel engines, and each formula delivers strong wear protection, low oil consumption, and rock-solid performance in extreme conditions.

What Your Diesel Deserves

Doc’s Diesel Oils are built to protect hard-working diesel engines, and each formula delivers strong wear protection, low oil consumption, and rock-solid performance in extreme conditions.

Customer Reviews

FREQUENTLY ASKED QUESTIONS

What’s your shipping policy?

We offer free shipping over $99 on all orders within the contiguous United States. Expedited shipping is available for an additional charge. Alaska, Hawaii, and Canada will have shipping fees.

Where does Doc’s Diesel ship to?

We ship to the U.S. and Canada! For Canada orders, any taxes, duties, or customs fees are the responsibility of the buyer. We handle orders in 1-2 business days, and most of the time in less than 24 hours if ordered on a week day. Depending on location, U.S. orders will arrive between 3-5 business days from your order. Canada orders typically arrive within 7-11 days.

What is your warranty?

View our Official Limited Warranty

Doc’s Diesel Filters meet or exceed Original Equipment Manufacturer’s (OEM) requirements. New vehicle warranties stay in effect when Doc’s Diesel filters are installed correctly and in conjunction to engine manufacturer’s recommendations.

Where is my order?

If you have not received your confirmation email us sales@docsdiesel.com so we can get everything sorted out ASAP. If you received a confirmation but no shipment email, we are still working on your order. Don't hesitate to email sales@docsdiesel.com if you would like more information and we'd be happy to check on your order. Please Include your order # in the email.

For Tracking information, it will be in your shipment email. Check the tracking # first or the latest updates. Doc's Diesel, just like you are at the mercy of shipping companies after a shipment leaves our warehouse. If there's been an issue with shipment we will happily work with you to figure out where the order is and what we can do to help. You can reach out to sales@docsdiesel and include your order # in the email. Thank You!

Why didn’t I get a confirmation email?

Sometimes an email may get sent to your spam folder! So don’t forget to check that. If you need more help to hesitate to reach us at sales@docsdiesel.com.

How do I start a return?

If you are unhappy with your purchase for whatever reason, and it's within 30 days from your purchase, you can return your diesel filters back to us. Item has to be in new condition. Once filters are received, we will refund your money (minus price of return shipping) within 2-4 business days. We will refund to your original form of payment. 

To start a return, visit our Returns Center.

View Our Official Limited Warranty Policy

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