Which 15w40 Oil is Recommended For Your Diesel?

Investing in a car is a costly venture that will set you back a handsome amount of bucks, and it is thus essential to take care of it to ensure that it can serve you for many years to come. Having efficient engine oil goes a long way in adding years to your car’s life and ensures that in case of a resale, you can get your money’s worth.

You will often hear that diesel engines require lots of oil changes and frequent checks to ensure that they remain clean and protected from damage, and this is true. What’s more, using an efficient diesel oil will enable your engine to run at optimum even when it is under lots of pressure.

Below, we will get into the definition of engine oil, why you need it, and what you should consider when making a selection. Additionally, we will cover the top five products in the market at present to make your decision-making easy. Here goes:

List & Comparison of the Best 15w40 Diesel Oils:

Shell Rotella T T4 Shell Rotella T T41 GallonCK-4View on Amazon
Ford XO-15W40-5QSD Ford XO-15W40-5QSD5 QuartC-4View on Amazon
Mobil 1 112786 Mobil 1 1127861 GallonCK-4View on Amazon
Royal Purple 04154 Royal Purple 041541 GallonCI-4View on Amazon
Lucas Oil 10076-PK4 Lucas Oil 10076-PK41 GallonCI-4View on Amazon

What is it?

Many people often confuse diesel oil with fuel oil, but there is a difference between the two as you use the former to lubricate your engine. When making a selection, you should look into the compatibility of your engine with the oil as this will enable your vehicle to run smoothly and efficiently.

Diesel engine oils are quite similar to gasoline engine oils, but the difference comes in with the additives in place. Diesel engine oils have more additives as they work on surfaces that operate in harsh conditions.

Review of the Best 15w40 Diesel Oils:

Shell Rotella T T4 — 15w40 Diesel Oil

Shell Rotella T T4

This diesel oil is a product of Shell Rotella, and you can thus rest assured that you are getting a technically advanced engine oil that will serve the needs of your engine for a long time to come.

It features advanced additive technology which protects the engine and enables it to perform optimally under pressure and also provides protection from viscosity loss. Additionally, it leads to enhanced oil aeration.

It features acid control, which ensures the engine stays protected from acids as well as deposit control, which enables the engine to remain clean and run optimally for a long time. The wear control feature ensures that the moving metal surfaces stay apart, and this adds on to the life of the engine.

You can use this engine oil in on-highway fleets, construction, pickup trucks, high-power vehicles as well as other engines that operate under pressure.

Product Features

  • Advanced additive technology
  • 7.5 pounds
  • Heavy duty diesel engine oil
  • Acid control
  • Deposit control
  • Wear control


  • Protects the engine from acid corrosion
  • Keeps the engine clean
  • Protection from viscosity loss
  • Enhanced oil aeration
  • Enhances engine performance

Ford XO-15W40-5QSD — 15w40 Diesel Oil

Ford XO-15W40-5QSD

This diesel oil features additive technology and works to enhance the performance of the engine.

The good thing about using this engine oil is that it does not void the warranty requirements of Ford Motor Company as well as most of the other engine manufacturers, provided you check with them first before making the purchase.

Product Features

  • 9.4 pounds
  • 5-quart capacity
  • Premium hydro-processed base oils
  • Additive technology
  • Compatible with Ford Motor Company requirements


  • Improves oil aeration
  • Doesn’t void Ford Motor Company warranties
  • Usable in old engines
  • Enhances engine performance
  • Works for power shift applications

Mobil 1 112786 — 15w40 Diesel Oil

Mobil 1 112786

This diesel oil features great soot-viscosity control, which allows the engine to perform efficiently and serve your car’s needs for a long time. Additionally, it has oxidation and thermal stability, which prevents the buildup of deposits and sludge, which can interfere with an engine’s performance.

The enhanced TBN reserves work great at protecting the engine from corrosion, and it thus increases drain intervals for engines. The oil consumption control reduces the make-up oil requirements, which lowers the costs of operation.

Product Features

  • Soot-viscosity control
  • Thermal stability
  • Oxidation stability
  • Enhanced TBN
  • Shear stability


  • Reduced oil usage
  • Added energy efficiency
  • Reduction of engine deposits
  • Keeps the engine running efficiently
  • Corrosion protection

Royal Purple 04154 — 15w40 Diesel Oil

Royal Purple 04154

This synthetic blend oil is one of the easiest ways to enhance engine performance. It features additive technology that prevents contact between metal, which reduces friction and thus leads to optimal fuel usage.

The ZDDP additive in play increases the efficiency of the catalyst systems. This diesel oil works great for engines that perform under a lot of pressure, such as in the heavy haulage sector.

Product Features

  • Enhanced additive technology
  • No rust oil
  • Patented ZDDP additive
  • One gallon capacity
  • Compatible with mineral and other synthetic oils


  • Great wear protection
  • Improved fuel efficiency
  • Protection of the catalytic emission system
  • Compatible with ethanol-containing fuels
  • Enhanced corrosion protection

Lucas Oil 10076-PK4 — 15w40 Diesel Oil

Lucas Oil 10076-PK4

This diesel oil lasts as much as twice the regular 15W-40 oils and is thus an excellent choice for anyone looking to enjoy a clean engine for a long time. The good thing about it is that it holds lots of soot in suspension than standard oils.

From using this oil, you can expect enhanced drain intervals and leads to improved engine life with no dry starts. It works excellent for engines under pressure owing to its high degree of lubrication.

Product Features

  • High-quality base oils
  • Additive package
  • SAE viscosity of rating 15
  • Lasts longer than standard 15W-40 oils
  • Usable in pre-2007 trucks


  • Enhanced lubrication
  • Improved drain intervals
  • Low operating temperatures
  • High oil pressure
  • Enhanced oil aeration

Diesel engine vs. a gasoline engine

Having a diesel engine affords you many benefits including reliability and ruggedness, as well as fewer maintenance costs and quiet operation. Also, these engines are safer than gasoline engines as they are unlikely to be flammable, hence their use in armored vehicles.

Additionally, they provide high mileage and are thus preferable for heavy-duty haulage. You may argue that diesel engines are more costly, but they have more density, which makes extraction of energy more accessible.

Diesel engines are also much more efficient and cost-effective as compared to gasoline engines and provide that you give the engines adequate maintenance, they will serve you for a long time.

What should you consider when making a selection?

You should consider the viscosity grade indicated as well as that which the equipment manufacturer stipulates as this will enable you to decide on the starting temperature of the engine. In this way, you will get a lubricant that can offer optimal performance even when working under pressure.

Cleaning capability is also essential as you want to choose a diesel oil that effectively cleans your engine and leaves it running smoothly.
What is the wear protection of the engine? The diesel oil you select should provide your engine with protection to increase its lifespan, without damaging it.

In this line, you should also consider its compatibility with your engine, versatility, and efficiency levels.

Bottom Line

When making a selection, it is easy to consider the cost as opposed to the quality of the oil. However, you should note that there are cheap options on the market that will not offer you the service that you deserve. At the same time, expensive diesel oils will not necessarily work great for your engine, and you are safest gauging the suitability of the products by other factors before you zero in on the cost.

About the author

Jim Malkovich

If you have any ideas or seek cooperation in any way, contact me today and let’s see where this leads us to. You can reach me at [email protected]

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