HEAVY DUTY DIESEL ENGINE OIL
Resists Viscosity Loss
Extreme Temperature Protection
Superior Thermal Stability
Low-Ash Formulation
Maximized Engine Protection
Advanced additives fight wear and heat, ensuring shear stability and longer oil life.
Extreme Temperature Protection
Low-temp fluidity ensures fast cold starts and quick lube flow in freezing conditions.
Proven Clean Performance
Oxidation and thermal stability reduce sludge while low-ash chemistry protects DPF systems.
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
Doc's is great to deal with even with their recent move to the new facility the order was fast and on time. Great service and products are priced comparable to others yet the quality is much better.
Only oil and filters I run in my Cummins! It’s here to stay. Outstanding products 🤙🏾
This is the first time I buy Docs diesel motor oil for my truck and I’m more than happy with my purchase. Excellent quality, good delivery time and a platform easy to deal with.
Thank you dock diesel!
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
Doc’s diesel has proven to have quality parts that i am proud to use in my truck definitely recommend to all my diesel brothers and sisters
I use the filter and oil kits to service my fleet of truck (4). I own a landscaping company and we are hard on our trucks, and it’s nice to have a convenient way to buy the correct amount of oil and all filters in one place.
What an easy purchase a two days latter I received everything. I will be a customer till I no longer need a diesel truck. I wish they carried stuff for gas vehicles.
Absolutely love it! And I WILL be getting this for now on
I love how easy it was to purchase and the price is great for this high end of oil. My only complaint is the shape of oil container makes it really hard to pour even into a funnel. Apart from that I love the oil
Changed all my filters and oil all at once. •fuel•oil •cab•air•crankcaseIt’s truly a one stop shop. With quality and no price gouging
This oil is a bit more pricey than off the shelf synthetic from your big box store but if you believe that it has been improved on over the off the shelf it seems to be a good deal. I just did a full service on my 2020 Denali Duramax using all Doc’s products and am pleased. Just wish it was all American made products.
Perfect and everything fit nicely
Love Hot Shot products. I was thrilled to when I seen they had paired with an oil company. 2007.5 LMM Duramax with 289k miles running quiet with this oil. I also run the 5w-40 diesel oil in our 2004 Jeep Wrangler with over 305k miles on it. Will definitely be ordering more for future oil changes!
So far so good in the 6.0 Powerstroke. A little pricey but the 6.0 seems to be running better with it than Rotella T6. Just over 1K on this oil, will have to wait to see how it does after 5K miles of use.
Oil and filters arrived as described. No issues at all
Doc's Diesel 10W-30 Full Synthetic Heavy-Duty Diesel Oil
So far I think it’s been great I’ll see in few months but really seems like a great product I ordered 4 more gallons for my next oil change
When the shipping company damaged my product and removed one item to try to hide it, Doc’s came through with service and shipped me a replacement on them fast! I will be a repeat customer for all my diesel needs.
I’m not using another brand of oil this is it.
Doc's Diesel 10W-30 Full Synthetic Heavy-Duty Diesel Oil
I like the fact with a couple clicks and the product shows up at my door.
Great product
Doc's Diesel 5W-40 Full Synthetic Heavy-Duty Diesel Oil
Doc's Diesel 15W-40 Full Synthetic Heavy-Duty Diesel Oil
Been using docs for all my truck needs. Very happy with the results and the fast shipping.
I've been using Doc's for all my maintenance supplies for several years. Always on time, great customer service
Highly recommend all products
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!