Changing your engine oil at regular intervals is the single most important task you should do. Timeous oil changes extend the life of your Jeep by protecting its engine internals better during startup and in harsh conditions. But what engine oil type should you use on your Jeep?
There are 3 types of oils:
- Regular Oil
- Synthetic blends
- Fully Synthetic
Regular oil changes at appropriate intervals as specified by your manufacturer are the key to engine longevity, not necessarily if it is conventional, synthetic blends, or full synthetic. The owner’s manual does not specify conventional or synthetic oil for the engine.
One thing for sure is, there has never been an engine that has failed directly as a result of using regular oil, blend, or synthetic oil. So before you select which oil type to use, there are a few important factors to take into consideration.
These factors are:
- Are you regularly driving in extreme conditions? (Extreme hot/cold weather conditions)
- Is cost a factor or do you simply want the best oil available for your Jeep?
- Does your Jeep have high mileage? (200K+ miles)
- What type of oil has it been using up until now?
Once you determine your Jeep’s operating environment and the other above factors, you are eliminating the need for either overly-expensive oils or you might need to invest in a more advanced oil for better protection.
Extreme weather conditions are a major differentiating factor when selecting oil. If you live in an area that experiences sub-zero temperatures, then synthetic oil with a 0W-30 rating is a better option. This offers protection from cold startup because it has a lower viscosity and additional additives that protect your engine in cold temperatures. However, if you live in a city where weather conditions are “normal” then regular oil works just fine. Conventional oils are less expensive and do a good job of protecting your engine. If you want to get fancy and be pedantic about it, you can use a 5w-30 for harsh operating conditions and a 10w-30 for normal weather conditions.
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Should I Use Synthetic Oil In My Jeep Wrangler?
This is a very contentious topic and if you ask 10 people if you should use synthetic oil vs regular oil in your Jeep, you’ll get 10 different answers. The confusion or differences in owners’ opinions came about when the marketing and sales departments of Massive Oil manufacturing companies, decided to start hyping certain types of oil and punting one type above another. Some people buy into the marketing information and choose only to use the best quality, highest grade, fully synthetic oil available, paying the premium price. While other Jeep owners claim to be using regular oil for decades and experiencing no problems AT ALL!
Synthetic Oil & Leaks
There are many reports of owners using regular oils in the jeeps without any hassle for many years, then later switching to synthetic oils, only to develop oil leaks. After reverting back to regular oil, the leak miraculously stopped, and the owner vowed never to touch synthetic oil again. Now, you can decide if that was related to the oil switch or not, I’ll just leave that there as an FYI.
Does Oil Brand Really Matter?
What we do know for a certainty is that the oil brand you choose makes little to no difference anymore, since all modern oils produced by major companies are fantastic. I’m sure we can all agree that brand name is rather down to personal preference. If you prefer the way the Mobil 1 container looks over the Royal Purple, and they are both of similar grade, that’s completely your call. Nobody can confidently say with scientific evidence that one major brand is better than the other, it’s all a matter of opinion. Since the invention of multi-viscosity oil, it doesn’t much matter what brand or oil type you use. Just continue changing the oil and the oil filter every 3-5k miles (FSM stipulates 3k).
3000-Mile vs 5000-Mile Oil Change Intervals
There are two trains of thought when it comes to oil change intervals. On the one hand, we have a manufacturer who specifies an oil change interval of 3,000-5,000 miles. There are many owners who swear by 3,000-mile oil changes, yet others are happy to let it run to the 5K mark. Then there are marketing companies who aggressively punt the 3,000-mile oil changes, for obvious reasons. They use terms like oil discoloration, contamination, and oil breakdown to build their case.
Whatever side of the fence you are on, it’s totally ok. If I must offer my personal opinion here, I tend to agree with the shorter oil changes and oil service intervals. Then again I drive a high-mileage diesel.
The most important factor to remember is, oil is the lifeblood of your truck and clean oil is the number one important factor to protecting your engine and its longevity. If oil costs per year are not a factor for you, then so be it, change your oil as regularly as possible. I personally don’t care what it costs me per year for oil changes. I changed my own oil on every rig I’ve ever owned. Heck, I change my mind every 3 minutes too.
Let’s now look at what the main causes of oil degradation are, and why it’s so important to change your oil regularly.
Combustion Contaminants
There are so many contaminants that break down your engine oil.
| Water (Cooling system) | Rapid Oil Breakdown |
| Coolant (Cooling System) | Rapid Oil Breakdown |
| Soot (Exhaust) | Gradual Breakdown |
| Acid & sludge (Exhaust) | Gradual Breakdown |
| Fuel (Combustion) | Gradual Breakdown |
When your engine is operating, all these contaminants slowly break down the oil viscosity over time. The combustion by-products can slowly leak past valve guides, piston rings, and other seals which include acid particles, carbon, moisture, and partially burned fuel, which all contaminate the oil. When oxidation takes place as a result of your oil coming in contact with hot engine components, these contaminants are formed. Also, if your engine is using water and it mixes with the oil, rapid oil breakdown occurs.
So there are naturally occurring contaminants that mix with the oil, and the buildup of contaminants and breakdown of the oil is what you should be concerned about, more so than oil type or brand. Regular servicing will reduce the breakdown damage and extend the lifespan of your engine. If your engine oil is clean, your Jeep will repay you with endless reliable miles with smiles. Just don’t forget to change the oil filter too!
Best Oil for Jeep Wrangler
The best oil for your Jeep Wrangler is clean oil. Irrespective of the type, may it be full synthetic or regular oil. What doesn’t or shouldn’t change is the oil replacement intervals. It doesn’t mean because you are using a more expensive, premium oil brand, you can now extend the interval of your oil changes.
Sure, you can argue that synthetic oil, theoretically lasts longer than regular oil, however, synthetic oil still gets contaminated at the same rate as regular oil. With that being said, oil change intervals should be the same for conventional and synthetic motor oils because of the reasons stipulated above.
Jeep owners recommend any of the below brands:
- Mobile 1 High Mileage Full Synthetic (10W-30)
- Royal Purple 5w-20
- Valvoline 5W-30
Mopar recommends using six quarts of 5W-20 oil. Depending on your driving conditions (extreme heat/cold) you can also use 5W-30.
What you’ll need For an Oil Change:
- 6 quarts of 5W-20 or 5W-30 (Weather Conditions Depending)
- New Oil Filter
- Ratchet
- 13mm Socket for oil pan bolt
- 24mm Socket for the oil filter
- Drain Pan
- Shop Towels / Paper Towels/cardboard
Does Jeep Use Synthetic Oil From The Factory?
Jeeps are filled up with Mopar 68218890AB 5W20 Engine Oil
This is regular oil and the exact same oil found in your engine when you purchased it from the dealership. If you were to have your Jeep serviced at the dealership they would use this oil.
The factory service manual recommends an oil change every 3000 miles.
This service interval is fit for the vehicle being used for:
- Off-roading
- Towing
- City driving
- Dry dusty conditions
It is not recommended to extend the service interval simply because you are using an expensive fully synthetic oil. The rate at which the oil gets contaminated is still the same. Stick to the Mopar recommendations.
Resources
Mobil 1 High Mileage 10w-30 (Full Synthetic) 6-Pack
Royal Purple 10w-30 Full Synthetic
Penzoil 10W-30 Conventional Oil
Wrangler 4cyl & 6Cyl Service Manual
Conclusion
Sticking to the manufactures recommendation of 3000-5000 mile oil changes is the safest way to go. Hop online and you’ll find many who claim they change it every 10 000 miles without hassle. If you do your own research you’ll realize 3-5k mile oil changes are best practice. The oil service parts are so cheap in comparison to the related problems you’ll run into caused by heavily contaminated oil. Why risk it? On the contrary, we have yet to see any proof that changing oil more often hurts your engine.
A smooth reliable engine isn’t the result of premium fully synthetic engine oils changed at 10,000-mile intervals, but rather the regular changing of the oil and filter at recommended intervals.