20 Best Synthetic Oil 15w40 [2025]

Are you looking for the best Synthetic Oil 15w40? Based on expert reviews, we ranked them. We've listed our top-ranked picks, including the top-selling Synthetic Oil 15w40.

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# Preview Product
1 Lucas Oil 10299-PK4 Synthetic 15W-40 CJ-4 Truck Oil - 1 Gallon Jug, Pack of 4 Lucas Oil 10299-PK4 Synthetic 15W-40 CJ-4 Truck Oil - 1 Gallon Jug, Pack of 4
2 Schaeffer Manufacturing Co. 0700CK4-012 SynShield Durability Advantage 15W-40 Diesel Engine Oil,... Schaeffer Manufacturing Co. 0700CK4-012 SynShield Durability Advantage 15W-40 Diesel Engine Oil,...
3 Ford Genuine XO-15W40-5QSD SAE 15W-40 Super Duty Diesel Motor Oil - 5 Quart Jug Ford Genuine XO-15W40-5QSD SAE 15W-40 Super Duty Diesel Motor Oil - 5 Quart Jug
4 Mobil 1 112786 Delvac 1300 Super 15W-40 Diesel Engine Oil - 4 Gallon Pack Mobil 1 112786 Delvac 1300 Super 15W-40 Diesel Engine Oil - 4 Gallon Pack
5 Mobil Super 96819 15W-40 Delvac 1300 Motor Oil - 1 Gallon (Pack of 4) Mobil Super 96819 15W-40 Delvac 1300 Motor Oil - 1 Gallon (Pack of 4)
6 Royal Purple 06154 Motor Oil - 15W40 CJ-4-6 pack Royal Purple 06154 Motor Oil - 15W40 CJ-4-6 pack
7 Triax Fleet Ultra ESP 15W-40 API CK-4 Licensed Synthetic Blend, Moly and Boron Performance Boosted,... Triax Fleet Ultra ESP 15W-40 API CK-4 Licensed Synthetic Blend, Moly and Boron Performance...
8 Delo 222290428 400 SDE SAE 15W-40 Motor Oil - 5 Gallon Pail Delo 222290428 400 SDE SAE 15W-40 Motor Oil - 5 Gallon Pail
9 15W40 CK-4 Synthetic Diesel Engine Oil - 55 Gallon Drum 15W40 CK-4 Synthetic Diesel Engine Oil - 55 Gallon Drum
10 Lucas Oil 10076-PK4 15W-40 Magnum High TBN Truck Oil - 1 Gallon Jug (Pack of 4) Lucas Oil 10076-PK4 15W-40 Magnum High TBN Truck Oil - 1 Gallon Jug (Pack of 4)
11 Delo 400 SDE SAE Conventional Heavy Duty Diesel Engine Oil 15W-40,1 Gallon, Pack of 3 Delo 400 SDE SAE Conventional Heavy Duty Diesel Engine Oil 15W-40,1 Gallon, Pack of 3
12 Mobil 1 Turbo Diesel Truck Full Synthetic Motor Oil 5W-40, 1 Gal Mobil 1 Turbo Diesel Truck Full Synthetic Motor Oil 5W-40, 1 Gal
13 Hot Shot's Secret Blue Diamond Full Synthetic PAO 15W40 Diesel Oil 1 Gallon Hot Shot's Secret Blue Diamond Full Synthetic PAO 15W40 Diesel Oil 1 Gallon
14 Castrol 03111C GTX High Mileage 10W-40 Synthetic Blend Motor Oil, 5 Quart Castrol 03111C GTX High Mileage 10W-40 Synthetic Blend Motor Oil, 5 Quart
15 Triax Fleet Supreme ESP 15W-40 API CK-4 Full Synthetic Diesel Engine Oil, Friction Optimized and... Triax Fleet Supreme ESP 15W-40 API CK-4 Full Synthetic Diesel Engine Oil, Friction Optimized and...
16 Valvoline VV70506-05 Premium Blue 15W40 Motor Oil, 5 gallon Valvoline VV70506-05 Premium Blue 15W40 Motor Oil, 5 gallon
17 Ford Oil - Engine Ford Oil - Engine
18 Mobil Super 96819 15W-40 Delvac 1300 Motor Oil - 1 Gallon (Pack of 4) Mobil Super 96819 15W-40 Delvac 1300 Motor Oil - 1 Gallon (Pack of 4)
19 Hot Shot's Secret Green Diamond 100 Percent Synthetic 15W40 Oil Diesel 1 Gallon Hot Shot's Secret Green Diamond 100 Percent Synthetic 15W40 Oil Diesel 1 Gallon
20 15W40 Diesel Engine Oil - 55 Gallon Drum 15W40 Diesel Engine Oil - 55 Gallon Drum
Bestseller No. 1
Lucas Oil 10299-PK4 Synthetic 15W-40 CJ-4 Truck Oil - 1 Gallon Jug, Pack of 4
  • For best performance, follow the manufacturer's recommendations in your vehicle owner’s manual.
Bestseller No. 2
Schaeffer Manufacturing Co. 0700CK4-012 SynShield Durability Advantage 15W-40 Diesel Engine Oil,...
  • Excellent wear protection during severe operating conditions
  • Oil durability: strong oxidation and viscosity control with less oil consumption
  • Better contamination control with superior soot-busting, deposit-dispersing capability
  • Strong stay-in-grade performance throughout the life of the oil
  • Friction modified with micron moly and penetrate
Bestseller No. 3
Ford Genuine XO-15W40-5QSD SAE 15W-40 Super Duty Diesel Motor Oil - 5 Quart Jug
  • High-quality diesel engine oil formulated with premium hydro processed base oils and unique additive technology
  • Package Dimensions: 11.176 L x 28.447 H x 23.114 W (centimeters)
  • Package Weight : 4.263 kilograms
  • Country of Origin : United States
Bestseller No. 4
Mobil 1 112786 Delvac 1300 Super 15W-40 Diesel Engine Oil - 4 Gallon Pack
  • Size: 1 Gallon
  • Type: 15w - 40
  • For usediesel engines requiring 15w-40 engine oil (referbottle for specifications)
  • Extends engine life with its unique additive system
Bestseller No. 5
Mobil Super 96819 15W-40 Delvac 1300 Motor Oil - 1 Gallon (Pack of 4)
  • Designed to deliver trouble-free, consistent performance
  • Right for your vehicle and lifestyle
  • Manufactured to meet or exceed strict quality requirements
  • If you have any questions or need fitment information for your vehicle, please contact with us
Bestseller No. 7
Triax Fleet Ultra ESP 15W-40 API CK-4 Licensed Synthetic Blend, Moly and Boron Performance Boosted,...
  • Contains built-in performance boosters for friction reduction, oxidation inhibition, shear, and viscosity stability
  • Nano borate and organic molybdenum reinforced for outstanding wear reduction and heat management; eliminates stiction and injector issues; frees most...
  • API licensed synthetic blend product for the latest API CK-4 New CK-4 spec
  • This product is backwards compatible with virtually all heavy-duty diesel engines from all years on both US, Japanese and European heavy-duty trucks...
  • Drain capabilities exceed 12,000 miles for farm trucks, 65,0000 miles for class 8 highway trucks, and 40,000 miles for in city, mixed traffic...
SaleBestseller No. 8
Delo 222290428 400 SDE SAE 15W-40 Motor Oil - 5 Gallon Pail
  • Premium quality, heavy duty motor oil manufactured in the USA
  • Formulated to meet the requirements of post-2007 low emission engines
  • Provides outstanding performance with ultra-low sulfur diesel and also with normal and low sulfur diesel fuels
  • May be used in older, conventional engines and gasoline engines
  • Formulated with ISOSYN technology
SaleBestseller No. 10
Lucas Oil 10076-PK4 15W-40 Magnum High TBN Truck Oil - 1 Gallon Jug (Pack of 4)
  • Package Dimensions: 12.75 L x 12.5 H x 12.75 W (inches)
  • Package Weight : 33 pounds
  • Country of Origin : United States
  • Part number: 10076PK4
Bestseller No. 11
Delo 400 SDE SAE Conventional Heavy Duty Diesel Engine Oil 15W-40,1 Gallon, Pack of 3
  • Premium quality heavy duty motor oil manufactured in the USA
  • Formulated to meet the requirements of post-2007 low emission engines
  • Provides outstanding performance with ultra-low sulfur diesel and also with normal and low sulfur diesel fuels
  • May be used in older conventional engines and gasoline engines
  • Formulated with ISOSYN technology
Bestseller No. 12
Mobil 1 Turbo Diesel Truck Full Synthetic Motor Oil 5W-40, 1 Gal
  • Mobil 1 Turbo Diesel Truck Is Designed For Modern Diesel Truck Engines, Delivering Long Drain Capability, Exceptional Performance, And Potential Fuel...
  • Meets Or Exceeds The Demanding Specifications Of Major Truck Manufacturers - One Engine Oil Can Be Used For Mixed Fleet Operations
  • Recommended For Use In All Super High-Performance Diesel Applications, Including Low Emission Engines
  • Helps Engines Last Longer By Reducing Low-Temperature Sludge Buildup And High-Temperature Deposits
Bestseller No. 13
Hot Shot's Secret Blue Diamond Full Synthetic PAO 15W40 Diesel Oil 1 Gallon
  • Improves fuel economy up to 3%
  • Lowers oil consumption
  • Reduces wear 71% over CJ-4
  • Improves power
  • Reduces friction
Bestseller No. 14
Castrol 03111C GTX High Mileage 10W-40 Synthetic Blend Motor Oil, 5 Quart
  • Superior detergency that helps prevent deposit build up
  • Superior oil burn off protection versus leading conventional oils
  • Seal conditioners help reduce leaks; Bottle Color: Green
  • Advanced additives that help prevent engine wear
Bestseller No. 15
Triax Fleet Supreme ESP 15W-40 API CK-4 Full Synthetic Diesel Engine Oil, Friction Optimized and...
  • CRP organic, metallic, Moly plating technology for unsurpassed wear protection, oxidation, and high temp stability
  • Friction modified and VI stabilizer pre-boosted; un-rivaled turbo-charger protection; will not create deposits and ash on turbo bearings (will not fry...
  • Contains state-of-the-art dispersal and ash control systems to keep your engine extremely clean
  • Extreme drain intervals capabilities; 25,000-mile drain interval for pickups and 80,000 for class 8 semi-trucks
  • Eliminates the need to clean diesel particulate filters and is for use in virtually all diesel-powered pickups and heavy-duty trucks, both pre 2007...
Bestseller No. 16
Valvoline VV70506-05 Premium Blue 15W40 Motor Oil, 5 gallon
  • Approved or Recommended for applications where Cummins CES 20086, Mack EOS-4.5, Volvo VDS-4.5, Detroit Diesel DFS 93K222, Renault VI RLD-4, Allison...
  • Approved or Recommended for applications where Detroit Diesel DFS 93K218 or Deutz DQC III-10LA are specfied
  • Excellent oxidation resistance and TBN retention supports long oil life
  • Strong shear stability provides stay-in-grade performance
Bestseller No. 17
Ford Oil - Engine
  • Country Of Origin: United States
  • Model Number: XO-5W40-5Q3SD
  • Item Package Dimension: 10.0" L x 11.0" W x 12.0" H
  • Item Package Weight: 12.0 lb
SaleBestseller No. 18
Mobil Super 96819 15W-40 Delvac 1300 Motor Oil - 1 Gallon (Pack of 4)
  • Reduced oil consumption
  • Superior low-temperature sludge control in stop-and-go service
  • Outstanding control of high-temperature deposits and oil oxidation
  • Reduced low temperature sludge build-up and high temperature deposits
Bestseller No. 19
Hot Shot's Secret Green Diamond 100 Percent Synthetic 15W40 Oil Diesel 1 Gallon
  • Hot Shot's Secret Green Diamond uses a unique blend of Group III base oils to improve your engine's fuel economy by up to 3 percent; specialized blend...
  • By improving fuel economy and reducing wear, Green Diamond Fleet Oil lowers your engine's overall fuel consumption by up to 78 percent compared to...
  • Compared to CJ-4 spec oils, Green Diamond Fleet Oil reduces wear and tear on your engine's components by 71 percent; synthetic oil product keeps your...
  • Green Diamond Fleet Oil uses patented FR3 nanotechnology lubrication with CK4 Additive packaging to keep your oil clean and increase your horsepower;...
  • Patented FR3 nanotechnology gets into the fine crevices of your engine to create smooth, slick surfaces that minimize metal-on-metal contact for the...

Having trouble finding a great Synthetic Oil 15w40?

This problem is well understood by us because we have gone through the entire Synthetic Oil 15w40 research process ourselves, which is why we have put together a comprehensive list of the best Synthetic Oil 15w40s available in the market today.

After hours of searching and using all the models on the market, we have found the best Synthetic Oil 15w40 for 2023. See our ranking below!

How Do You Buy The Best Synthetic Oil 15w40?

Do you get stressed out thinking about shopping for a great Synthetic Oil 15w40? Do doubts keep creeping into your mind?

We understand, because we’ve already gone through the whole process of researching Synthetic Oil 15w40, which is why we have assembled a comprehensive list of the greatest Synthetic Oil 15w40 available in the current market. We’ve also come up with a list of questions that you probably have yourself.

John Harvards has done the best we can with our thoughts and recommendations, but it’s still crucial that you do thorough research on your own for Synthetic Oil 15w40 that you consider buying. Your questions might include the following:

  • Is it worth buying an Synthetic Oil 15w40?
  • What benefits are there with buying an Synthetic Oil 15w40?
  • What factors deserve consideration when shopping for an effective Synthetic Oil 15w40?
  • Why is it crucial to invest in any Synthetic Oil 15w40, much less the best one?
  • Which Synthetic Oil 15w40 are good in the current market?
  • Where can you find information like this about Synthetic Oil 15w40?

We’re convinced that you likely have far more questions than just these regarding Synthetic Oil 15w40, and the only real way to satisfy your need for knowledge is to get information from as many reputable online sources as you possibly can.

Potential sources can include buying guides for Synthetic Oil 15w40, rating websites, word-of-mouth testimonials, online forums, and product reviews. Thorough and mindful research is crucial to making sure you get your hands on the best-possible Synthetic Oil 15w40. Make sure that you are only using trustworthy and credible websites and sources.

John Harvards provides an Synthetic Oil 15w40 buying guide, and the information is totally objective and authentic. We employ both AI and big data in proofreading the collected information.

How did we create this buying guide? We did it using a custom-created selection of algorithms that lets us manifest a top-10 list of the best available Synthetic Oil 15w40 currently available on the market.

This technology we use to assemble our list depends on a variety of factors, including but not limited to the following:

  1. Brand Value: Every brand of Synthetic Oil 15w40 has a value all its own. Most brands offer some sort of unique selling proposition that’s supposed to bring something different to the table than their competitors.
  2. Features: What bells and whistles matter for an Synthetic Oil 15w40?
  3. Specifications: How powerful they are can be measured.
  4. Product Value: This simply is how much bang for the buck you get from your Synthetic Oil 15w40.
  5. Customer Ratings: Number ratings grade Synthetic Oil 15w40 objectively.
  6. Customer Reviews: Closely related to ratings, these paragraphs give you first-hand and detailed information from real-world users about their Synthetic Oil 15w40.
  7. Product Quality: You don’t always get what you pay for with an Synthetic Oil 15w40, sometimes less, and sometimes more.
  8. Product Reliability: How sturdy and durable an Synthetic Oil 15w40 is should be an indication of how long it will work out for you.

John Harvards always remembers that maintaining Synthetic Oil 15w40 information to stay current is a top priority, which is why we are constantly updating our websites. Learn more about us using online sources.

If you think that anything we present here regarding Synthetic Oil 15w40 is irrelevant, incorrect, misleading, or erroneous, then please let us know promptly!

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FAQ:

Q: What is the different between 15w40 and 15w50?

A: thus for your question, 15W40 and 15W50 are equally viscous, but the ..50 will have more thickening polymers in it than the ..40. the 15W40 is more viscous than the 10W40. 0

Q: Who makes the best synthetic motor oil?

A: Castrol 03084 Edge. After years of research and experimentation,in 2019,Castrol discovered a groundbreaking new fluid titanium technology. Castrol 03087 Edge. Most premium synthetic motor oils become impure or contaminated after 6-7 months of use. … Valvoline – 881147. … Pennzoil Ultra Platinum. … AmazonBasics High Mileage. … Royal Purple 51530. …

Q: What is meant by 15w40 for generator?

A: For a gas generator, most people use plain SAE 30 because they don’t ever run in cold weather (below freezing) and SAE 30 is optimum for warmer weather (per the Onan Handbook). 10W30 or 15W40 is optimum if you want to cover sub-freezing temperature operation as well.

Q: What is the best synthetic oil?

A: The best synthetic motor oil is Mobil 1 94001 5W-30 with its outstanding wear protection due to superior lubrication in high to low temperatures. The reason car oil is so important is due to the fact it lubricates the engine to reduce wear and friction as well as protecting the break down of components from engine heat.