Jeep Wrangler’s Oils & Fluids

The type of engine oil your Jeep needs is largely dependent on the engine and your driving conditions, but it also depends on the climate your Jeep is in. 

What do the numbers mean? The first number in an engine oil’s classification includes the letter “W” which stands for Winter. This number is important for climates that are very cold, the lower the number the better it will perform in colder weather. The second number refers to the oil's viscosity within 100-degrees Celsius. The lower this number, the thinner the oil will be. Typically, you would use a thinner oil if you live in tolerable weather climates, allowing the engine to warm the oil and reach peak performance at a faster rate. If you live in extreme clients, the viscosity is important to keep in mind when considering optimal performance temperatures. 

Conventional or synthetic? The ongoing debate of conventional versus synthetic oil has always been unclear. Each type of oil has its benefits, but in large part the decision is largely based on your Jeep’s mileage and average driving conditions. Typically, high-mileage Jeeps that do an excessive amount of highway travel benefit more from synthetic engine oil. Jeeps with low mileage that typically see more trail use, that cause for frequent fluid changes, benefit more from conventional oil.

Wranglers have solid axles that require differential fluid to properly lubricate the gears. While driving heat and pressure builds in the gearing case, this pressure requires proper ventilation to prevent a blown gasket and leaking of the fluid. As a result, the differentials on Jeeps have breather tubes that allow the venting of gases. These breather tubes are capped and placed within the mid-way point of a Wrangler. Occasionally, during deep water crossing, water might enter the breather tubes and contaminate the differential fluid. As a result, it’s always good practice to change your differential fluid after any trail use that involved deep-water crossings, in addition to the regular maintenance schedule. The process of changing differential fluid is fairly straightforward and easy, but different differential configurations require different quantities of fluid. Below are the quantities and types of fluid used in a variety of differential configurations. 

Coolant is cooled through the Jeep’s radiator and circulates through the engine to cool and maintain the engine while driving. The coolant’s composition breaks down over time and requires monitoring and maintenance. Below are the quantities and types of coolant used in Wranglers.

It’s always good practice to continually check your brake fluid reservoir level; it’s also good practice to replace the brake fluid once every two years. Changing the brake fluid is a straightforward process, but requires some patience to ensure no air bubbles are left in the brake line. Utilizing a brake bleeder with a clear hose will help monitor the air bubbles as you bleed the brake lines. All Wranglers use DOT 3 brake fluid, making the maintenance even easier.

The Wranglers transfer case is an important part when engaging and working with the Jeep’s four-wheel-drive system. The complex grouping of gears requiring lubrication, which in turn also requires maintenance. Below are the breakdowns of fluids used for each transfer case.

As mentioned throughout this guide, all of your Wrangler’s fluids serve a specific function and all require monitoring and maintenance. Jeep’s service recommendations are good guidelines, but it’s important to monitor levels and replace the fluids according to your conditions and driving patterns. In addition, heavy trail use and deep-water crossings will have an impact on the quality and longevity of the fluids. Maintaining a good record and awareness of your Wrangler’s fluids will help ensure years of reliability.