Are you a proud jeep owner who is looking for the best oil for Jeep 4.0 engines?
If so, you are in the right place, as we have a wealth of information to share that will assist you in making a sound buying decision.
In this PopularMechanic.com guide, you will learn the following:
- What is Engine Oil?
- How Does Engine Oil Work?
- What are the Different Types of Engine Oil?
Below is a quick list of all our top products. Keep scrolling to learn more about how to choose the best oil for Jeep 4.0 engines.
Valvoline High Mileage with MaxLife Technology Synthetic Blend Motor Oil
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Pennzoil Conventional 10W-30 Motor Oil
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Royal Purple SAE High Performance Synthetic Motor Oil
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Mobil 1 High Mileage 10W-30 Motor Oil
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Castrol 03129C EDGE High Mileage 10W-30 Advanced Full Synthetic Motor Oil
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Our Overall #1 Rated Pick
Our overall best choice for Jeep 4.0 engine oil is Valvoline High Mileage 10W30 with Maxlife Technology.
Valvoline High Mileage 10W30 with Maxlife Technology-enhanced detergent additives gently sweep away a lifetime's worth of sludge, while included seal conditioners keep your 4.0 engine free of leaks.
This oil caters to the era of the Jeep 4.0 engines.
The inline 6-cylinder, 4.0 liter is perhaps the most iconic of all jeep engines.
This stout little workhorse, served the Jeep Wrangler, Jeep Cherokee, and Jeep Grand Cherokee well through many years of production, and continues to do the same for most of these classic jeeps today.
As long as regular service was conducted, it seemed that the 4.0 engine would run forever.
Luckily, we have located the best oils to complete just such a task, which are sure to take your six-cylinder engine’s durability to the next level.
Top 5 Best Engine Oils For Jeep 4.0 Engines
What Is Engine Oil?
Engine oil is a lubricating substance that resides within the crankcase of an internal combustion engine.
The purpose of this oil is to cut down on the wear and tear of internal engine parts and components, by minimizing metal to metal friction. Which is exactly why choosing a good oil is essential to your car's function.
This prevents premature engine wear and provides year-round protection to your car’s engine.
However, motor oil does not remain effective indefinitely. With time, the level of engine protection that is provided by oil drops as additive packages within begin to break down.
To combat this, every vehicle has a regularly scheduled oil change interval. These intervals can be found in a vehicle’s owner’s manual.
How Does Engine Oil Work?
There are a number of moving parts located within an internal combustion engine.
This motion causes friction. Friction leads to the building of heat, and the erosion of surface material, both of which are bad for your vehicle’s engine.
Engine oil is tasked with the job of minimizing this friction, and the detrimental effects that come with it.
Oil is circulated about an engine with the use of the oil pump.
This pump assures that all components are adequately lubricated and free of excess wear.
Prior to being directed to an engine’s internal components, oil first passes through an oil filter where it is strained for any contaminants or metal shavings.
As oil runs from individual components, it is redirected into the engine’s oil pan, where the oil is again picked up by the pump.
As oil flows within an engine, operating temperatures are reduced, and fuel economy is slightly increased due to seamless engine operation.
Check out this article for more on how engine oil works.
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What Are The Different Types Of Engine Oil?
When discussing different types of motor oil, much of what separates oils from one another comes down to composition.
This composition consists of a base oil and additives.
Base oil can either be of a conventional nature or synthetic makeup, and additives can range significantly from one oil to the next.
These additives can include detergents, dispersants, friction modifiers, and viscosity index improvers.
The combination of this base stock and additives defines an individual type of oil.
The following are the most common types of engine oil.
Conventional motor oil consists of a basic, refined petroleum type base stock, that is fortified with additives such as detergent packages to prevent deposits and other forms of build-up.
In most cases, conventional oil is the least expensive variety of motor oil, yet is still highly effective in most vehicles and driving scenarios.
However, those who prefer the use of conventional oil must stay on top of oil change intervals, as this oil type does not resist breakdown as well as synthetic alternatives.
High Mileage Oil
High mileage motor oils can differ substantially in their composition.
However, the overall goal of these oils is to provide your aging engine with added protection, in order to keep it running strong well into its twilight years.
In many cases, high mileage variants consist of a conventional oil base with specialized additives.
Alternatively, a number of high mileage products actually consist of a synthetic blend oil, that provides a mix between conventional and synthetic oil technologies.
Synthetic motor oil is engineered to outlast and outperform conventional motor oil, in almost any circumstance.
Full synthetic oil is also known for its ability to withstand high demand driving conditions and resists breakdown.
In many cases, the time between oil change intervals is extended when synthetic oil is used, due to its overall resilience and longevity.
While synthetic motor oil is undoubtedly the most expensive of all oil types, this price difference is typically offset by a less frequent maintenance schedule.
To learn more about the different types of oils, check out this article.
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What To Look For In Engine Oil for Jeep 4.0 Engines
During Cold Weather:
In the cold weather of the winter months, you must pay close attention to your engine oils viscosity rating.
The viscosity of a particular oil directly determines how it reacts in certain temperature ranges.
The viscosity rating of a particular oil is notated by a given viscosity rating, such as 5W-30, 10W-30, and 15W-40.
These various SAE (Society of Automotive Engineers) designations for oil weight are your guide to understanding how oil will flow at a particular temperature.
For example, 5W-30 would flow like SAE 5W at lower temperatures and SAE 30W at higher temperatures. Therefore the lower the first number of a given oil’s SAE designation is, the better it will perform in cold weather.
For this reason, jeep owners should focus on heavier oils with a 5W SAE designation, when operating in harsh winter environments.
During Hot Weather:
SAE viscosity designations are equally important during the summer months when stifling heat can push your engine to its limits.
If your 4.0 liter equipped Jeep serves as your summer cruiser, an oil with a greater SAE winter rating is advisable.
In this case, many Jeep owner’s manuals called for the use of 10W30 weight oil. This allowed for excellent start-up protection, as well as reliable protection during high-end operation.
The use of 10W-30 motor oil also served as a happy medium for all points of operation in between.
Premium All-Season Protection:
Luckily, in the years since the 4.0 engine’s hay-day, a number of advancements have been made in engine oil technology, the biggest of which has been in the development of synthetic oils.
Synthetic oils are better able to maintain their protective qualities under a wide array of weather conditions, making annual changes from winter to summer oil a somewhat obsolete notion.
Today, the use of a quality synthetic 5W-30 oil will suffice for all-season protection for any 4.0 liter equipped jeep.
This saves Jeep owners time, money, and hassle, while also streamlining the maintenance practices associated with their Jeeps.
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Top 5 Best Oils For Jeep 4.0 Engines (2020 Review)
Valvoline is one of the most well-trusted names in the automotive oil manufacturing industry.
The company’s history dates back more than 150 years and is highlighted by its use in everything from police cruiser fleets to race cars.
Valvoline High Mileage with Maxlife Technology works to breathe new life into your aging Jeep, by wiping out the sludge that has accumulated during a lifetime of work.
Additionally, Maxlife contains specialty additives that rejuvenate seals to stop leaks in their tracks.
Much like the other manufacturers represented on this list, Pennzoil is one of the most storied oil manufacturers in the global market and sells millions of gallons of oil on a yearly basis.
Ever since its beginning, the company has turned out nothing but some of the finest oil and lubrication products in the industry.
Pennzoil 10W-30 is engineered to conquer the sludge and build-up that tends to be the undoing of many daily drivers.
Meanwhile, a comprehensive package of anti-wear additives minimizes wear from every angle, ever when facing taxing stop and go driving conditions.
While not as well known by many as the names Mobil 1, Pennzoil, Castrol, and Valvoline, Royal Purple has been coming on strong for quite some time in the oil manufacturing business, with a specialized emphasis in synthetic products.
In fact, Royal Purple carries much fanfare from those involved in high-performance functions.
Royal Purple boasts of their high-performance engine oil’s increased capacity to increase fuel efficiency and prolong catalytic emissions component longevity.
This oil also includes a comprehensive anti-wear additive package that attacks corrosion at its source.
Royal purple also provides stellar performance when aftermarket fuel variants are used.
Mobil 1 has been a pioneer of high-end motor oil technology for many years, and has been on the leading edge of numerous breakthroughs in that realm.
This has positioned the company as a perennial powerhouse within the engine oil market.
Mobil 1 High Mileage Full Synthetic 10W-30 is recommended for any vehicle with over 75,000 miles.
This oil is specially formulated to slow or stop any oil leaks, with the use of Mobil 1’s proprietary seal conditioner formula.
Mobil 1 High Mileage’s Synthetic makeup also means that this oil as well adept to handling any demands that you can put on your 4.0 liter Jeep.
Castrol is another name within the oil manufacturing industry that carries substantial weight.
Castrol has built quite a reputation for developing only products that meet the most stringent of quality demands.
Castrol EDGE High Mileage 10W-30 Advanced Full Synthetic utilizes a specialty titanium technology formula that allows oil to cling to friction surfaces far more efficiently than many competing brands.
This ensures that all of your engine’s components are continually supplied with essential lubrication under any circumstances.
My top pick for the best 4.0 Jeep engine oil is Valvoline High Mileage 10W30 with Maxlife Technology.
This oil is specially formulated to cater to 4.0 liter Jeep engines as they begin to age.
Although wonderful engines from top to bottom, the 4.0 was last produced a decade and a half ago, meaning the bulk of these engines are starting to reach the high mileage threshold.
Luckily, Valvoline Maxlife is specifically engineered to keep an engine of this status on the road.
Enhanced detergent additives gently sweep away a lifetime's worth of sludge, while included seal conditioners keep your 4.0 engine free of leaks.
This is a winning proposition, as two of the biggest enemies of aging engines are sludge build-up and leaks.
If you are looking to pamper your Jeep with the best motor oil money can buy, be sure to check out Valvoline High Mileage 10W30 with Maxlife Technology.
Plus, it's an excellent value for the money! Check the low price now on Amazon.
Do You Have Any Questions?
Feel free to contact us via our Proper Mechanic website and we'll get back to you with all the answers you need.