2018 Tesla Model X Fluid Type Specifications

Quick Reference

Fluid	Type/Spec	Capacity
Engine Oil	N/A (Electric Vehicle)	N/A
Engine Coolant	Glycol-based, Tesla-specific (e.g., Tesla G-48 equivalent)	~15-18 Liters
Transmission Fluid	Pentosin ATF 1 / Shell Spirax S5 ATF X	~1.9 Liters (front) / ~2.3 Liters (rear)
Transfer Case	N/A (No separate transfer case; AWD managed by dual motors)	N/A
Front Differential	Pentosin ATF 1 / Shell Spirax S5 ATF X	~1.9 Liters
Rear Differential	Pentosin ATF 1 / Shell Spirax S5 ATF X	~2.3 Liters
Brake Fluid	DOT 4 / DOT 4 LV (Low Viscosity)	Consult manual
Power Steering	N/A (Electric Power Steering)	N/A
Washer Fluid	Standard Windshield Washer Fluid	~4.5 Liters
DEF	N/A (Electric Vehicle)	N/A

Introduction to Tesla Model X Fluid Specifications

As an ASE-certified master technician, it's important to understand that electric vehicles like the 2018 Tesla Model X have significantly different fluid requirements compared to traditional internal combustion engine (ICE) vehicles. Many fluids associated with gasoline or diesel engines are simply not present. However, there are still crucial fluids that require attention for proper maintenance and longevity of your Tesla.

Engine Oil

The 2018 Tesla Model X is an all-electric vehicle and, as such, does not use engine oil. There is no internal combustion engine to lubricate. This eliminates a significant maintenance item for Tesla owners.

Engine Coolant

Even though there's no engine, the Tesla Model X utilizes a sophisticated liquid cooling system for its battery pack, power electronics, and electric motors. This system is critical for maintaining optimal operating temperatures and ensuring performance and longevity of the high-voltage components.

Tesla typically uses a specific glycol-based coolant that is formulated for its particular thermal management system. While the exact chemical composition can vary, it is generally a silicate-free, phosphate-free, and nitrite-free coolant, commonly resembling a HOAT (Hybrid Organic Acid Technology) or specific long-life OAT formulation. It is often blue or sometimes pink/purple in color.

Manufacturer Spec: Tesla does not publicize specific G-numbers or common industry designations with the same prominence as traditional OEMs. However, it's understood that the coolant should meet Tesla's internal specifications. Aftermarket equivalents often reference ethylene glycol-based G-48 equivalent coolants, but it is crucial to use only Tesla-approved coolant or a direct equivalent specified by Tesla service documentation. Mixing different coolant types, especially traditional OAT with HOAT or IAT, can lead to system corrosion, reduced cooling efficiency, and damaged components.

Capacity: The total cooling system capacity is approximately 15-18 liters, varying slightly by configuration.

Intervals: Tesla generally recommends checking the coolant level periodically and replacing it according to the maintenance schedule in your owner's manual or Tesla service recommendations, which can be every 4 years or 50,000 miles, depending on the model and driving conditions. Always verify the latest intervals in your owner's manual.

Transmission Fluid (Gearbox Fluid - Front & Rear Drive Units)

The Tesla Model X uses electric motors that drive the wheels through a single-speed reduction gear box (often referred to generically as a "transmission" or "gearbox"). There is a separate gear reduction unit for the front motor and another for the rear motor in AWD models. These units require a specific lubricating fluid.

Type/Spec: Tesla specifies a synthetic automatic transmission fluid for these drive units. Historically, fluids like Pentosin ATF 1 or Shell Spirax S5 ATF X have been referenced. These are premium, synthetic, multi-vehicle low-viscosity ATFs. Never use generic "universal" ATF or fluids not specifically approved by Tesla. Using the wrong fluid can lead to premature wear of the reduction gears and bearings.

Capacity: The front drive unit typically holds approximately 1.9 liters (2.0 quarts), and the rear drive unit holds about 2.3 liters (2.4 quarts). These capacities are for fluid changes; always confirm with your owner's manual or Tesla service documentation for exact fill levels, which typically involve filling to the bottom of the fill plug.

Intervals: Tesla generally recommends checking and potentially changing the drive unit fluid at intervals outlined in the owner's manual, which can be around 12 years or 150,000 miles, or as part of a general inspection. Some earlier recommendations were more frequent. Always refer to your specific owner's manual for the most up-to-date service intervals.

Transfer Case

The 2018 Tesla Model X is an All-Wheel Drive (AWD) vehicle, but it achieves this through independent front and rear electric motors. It does not have a traditional transfer case that would typically be found in ICE-based AWD/4WD vehicles. Therefore, there is no separate transfer case fluid.

Front and Rear Differential Fluid

Similar to the transmission fluid section, the "differential" in a Tesla Model X refers to the gear reduction units integrated with the electric motors for the front and rear axles. These units use the same specific lubricating fluid as mentioned above.

Type/Spec: Pentosin ATF 1 or Shell Spirax S5 ATF X are the specified synthetic ATFs. These are high-performance fluids designed to withstand the stress and heat generated within the drive units.

Capacity: As mentioned before, the front drive reduction unit capacity is approximately 1.9 liters, and the rear drive reduction unit capacity is about 2.3 liters.

Intervals: Refer to the same intervals as the "Transmission Fluid" section. These fluids are considered "lifetime" by some manufacturers, but for optimal longevity and performance, especially in vehicles that see spirited driving or frequent regenerative braking (which can stress the driveline), periodic inspection and possible replacement are good practice.

Brake Fluid

The brake system in a Tesla Model X is similar to that in conventional vehicles, requiring hydraulic brake fluid to operate the calipers.

Type/Spec: Tesla specifies DOT 4 or DOT 4 LV (Low Viscosity) brake fluid. DOT 4 LV fluids are particularly suited for vehicles with advanced ABS, traction control, and electronic stability control systems, common in Teslas. These fluids offer superior performance in cold weather and have a higher wet boiling point compared to DOT 3, which is important for maintaining braking performance over time. Never use DOT 5 (silicone-based) fluid, as it is incompatible with DOT 3/4/5.1 systems and can damage seals and components.

Capacity: The capacity will vary based on the system, but a typical brake fluid flush will require 1-2 liters of fluid.

Intervals: Tesla generally recommends checking the brake fluid level and replacing it every 2 years or 25,000 miles, or as specified in your owner's manual. Brake fluid absorbs moisture over time, which lowers its boiling point and can lead to corrosion in the braking system.

Power Steering Fluid

The 2018 Tesla Model X utilizes an Electric Power Steering (EPS) system. This means there is no hydraulic power steering pump, no power steering fluid reservoir, and therefore, no power steering fluid to check or replace. This is another maintenance item eliminated by the electric vehicle design.

Washer Fluid

Windshield washer fluid is a straightforward requirement for maintaining visibility.

Type/Spec: Use standard, off-the-shelf windshield washer fluid. Ensure it is suitable for your climate, especially if you live in an area with freezing temperatures, as freeze-protected formulas are essential. Some premium fluids offer bug-removing or rain-repelling properties.

Capacity: The washer fluid reservoir typically holds around 4.5 liters (1.2 gallons).

Intervals: Top up as needed. There is no specific replacement interval.

Diesel Exhaust Fluid (DEF)

The 2018 Tesla Model X is an all-electric vehicle and does not have an internal combustion engine that produces exhaust gases requiring treatment with Diesel Exhaust Fluid (DEF). Therefore, DEF is not applicable to this vehicle.

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