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HEAVY DUTY DIESEL ENGINE OIL
Resists Viscosity Loss
Extreme Temperature Protection
Superior Thermal Stability
Low-Ash Formulation
Maximized Engine Protection
Advanced additives guard key parts from heat and wear while resisting viscosity loss for longer oil life.
Extreme Temperature Protection
Low-temp pumpability delivers fast flow and protection in cold starts and harsh winter conditions.
Proven Clean Performance
Strong oxidation and thermal stability help prevent sludge and deposits for a cleaner-running engine.
Engineered for Emissions
Low-ash CK-4 formula supports DPF/EGR systems and meets GHG 2017 targets for lower emissions and better fuel economy.
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 RIGHT FOR YOU?
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
Customer Reviews
Very nice product at good price would recommend to anyone who likes to take of there dodge ram 6.7 Cummins like I do thank you Docs
Absolutely love it! And I WILL be getting this for now on
Perfect and everything fit nicely
Just got my first diesel about a year ago and did the first oil change and fuel filters at the dealership not knowing I’d have to sell a kidney to pay it. Second and from now on I used all Docs products and did it myself. Great oil, great package for maintenance.
I recently bought three gallons of oil from Doc’s. When I went to pay with my brand new phone the Apple Pay put in an old address in Florida. I’m in north Western Washington now so that couldn’t be any further away. A member of the staff pulled my order even after tracking had been created and was able to get the oil out to me in the same time frame it would have taken otherwise. Great customer service!
I love what Doc’s is doing, my one stop shop for my 6.7 Stroker. Products are premium quality and timely shipping..
Great Value, excited to see how this performs.
Thank you for your review of Doc's Diesel! We are thrilled to hear that you are satisfied with the quality and value of our product. We are confident that it will perform exceptionally for you. If you have any further feedback or questions, please don't hesitate to reach out to us. Thank you for choosing Doc's Diesel!
Not a single issue or problem. Gets the job done every single time
Great quality, fast delivery
Product was fine but where is my hoodie? I like hoodies. Bought more product to qualify for one. No hoodie. I’m a man of my word. Are you?
Hey Scott! Shoot us an email over at sales@docsdiesel.com and we can get this fixed up for you!
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
Thank you!