2018 GMC Acadia Fluid Specifications Guide

As an ASE-certified master technician, I’ve serviced countless modern SUVs, and the second-generation GMC Acadia is a frequent visitor to the bay. To keep your 2018 GMC Acadia running smoothly, using the exact manufacturer-specified fluids is not just a recommendation—it’s an absolute requirement. Modern tolerances are incredibly tight, and the wrong fluid can lead to catastrophic component failure, voided warranties, and massive repair bills.

Whether your 2018 Acadia is equipped with the 2.5L inline-four or the 3.6L V6, this guide covers every factory-spec fluid you need to know about.

Quick reference

Fluid	Type/Spec	Capacity
Engine Oil (2.5L I4)	5W-20 (GM dexos1 Gen 3 / API SP)	5.0 quarts (with filter)
Engine Oil (3.6L V6)	5W-30 (GM dexos1 Gen 3 / API SP)	6.0 quarts (with filter)
Engine Coolant	GM Dex-Cool (Orange, OAT)	2.5L: ~9.5 qts / 3.6L: ~11.8 qts
Automatic Transmission	GM Dexron® VI ATF	~4.2 - 6.3 qts (Drain & Fill)
Transfer Case (AWD)	75W-90 Synthetic Gear Oil (GL-5)	~0.8 quarts
Rear Differential (AWD)	75W-90 Synthetic Gear Oil (GL-5)*	~0.6 - 0.8 quarts
Brake Fluid	DOT 3 Hydraulic Brake Fluid	Fill to MAX line
Power Steering	Electric Power Steering (EPS)	N/A (No fluid required)
Washer Fluid	Standard windshield washer fluid	~1 gallon

*Note: AWD models with the twin-clutch active rear differential (common on All Terrain trims) may require GM Dexron LS Gear Oil 75W-90. Always verify your specific AWD RPO code in the owner's manual or OEM service info.

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Engine Oil

The lifeblood of your Acadia's engine is its oil. General Motors mandates the use of engine oil that meets the dexos1™ specification. While the 2018 manual originally called for dexos1 Gen 2, GM has superseded this with dexos1 Gen 3 (and API SP).

• 2.5L I4 Engine: Requires 5W-20 viscosity.
• 3.6L V6 Engine: Requires 5W-30 viscosity.

Intervals and Pitfalls: Rely on the GM Oil Life Monitor System (OLMS), but as a master tech, I recommend never exceeding 5,000 to 7,500 miles between changes, especially if you drive in stop-and-go traffic. Failing to use a dexos1-approved oil can cause premature wear on the timing chains—a known, labor-intensive weak point on the 3.6L V6 engine.

Engine Coolant

Your 2018 GMC Acadia uses GM Dex-Cool, which is an Organic Acid Technology (OAT) coolant, easily identifiable by its orange color (though some newer GM formulations appear slightly pink).

Intervals and Pitfalls: Dex-Cool is rated for 5 years or 150,000 miles. Never mix OAT (Dex-Cool) with HOAT, IAT (traditional green), or universal coolants. Mixing different coolant chemistries causes the corrosion inhibitors to drop out of suspension, forming a thick, brown sludge that will clog your heater core and radiator, leading to severe engine overheating. Always use a 50/50 mix of Dex-Cool and distilled water.

Automatic Transmission Fluid

Both the 2.5L and 3.6L engines are paired with a 6-speed automatic transmission (6T50 or 6T70 series) that exclusively requires GM Dexron® VI Automatic Transmission Fluid.

Intervals and Pitfalls: Under "severe" driving conditions (which most daily commuting falls into), GM recommends changing the transmission fluid every 45,000 miles. Under normal conditions, they state 97,500 miles. As a technician, I advise a drain and fill every 45,000 to 60,000 miles to keep the valve body and solenoids clean. Do not use universal ATFs. Universal fluids rarely meet the exact frictional requirements of Dexron VI, which can lead to harsh shifting, torque converter shudder, and premature clutch pack failure.

Transfer Case and Rear Differential (AWD Models)

If your Acadia is equipped with All-Wheel Drive, you have a transfer case (sometimes called a Power Transfer Unit or PTU) and a Rear Drive Module (differential).

Standard AWD systems require a high-quality 75W-90 Synthetic Gear Oil meeting API GL-5 specifications (GM Part No. 88900401). However, if you have the upgraded twin-clutch AWD system (usually found on All Terrain models), you must use GM Dexron LS 75W-90 (which contains a specific friction modifier for the clutches).

Intervals and Pitfalls: These fluids take a beating due to the small fluid capacities and high operating temperatures. I recommend replacing the transfer case and rear differential fluids every 30,000 to 45,000 miles. Neglecting this often results in PTU bearing failure—a highly expensive repair.

Brake Fluid

The 2018 Acadia utilizes conventional DOT 3 Brake Fluid.

Intervals and Pitfalls: Brake fluid is highly hygroscopic, meaning it constantly absorbs moisture from the atmosphere. Once the moisture content exceeds 3%, the boiling point of the fluid drops drastically, leading to a spongy brake pedal and reduced stopping power during heavy braking. It also causes internal corrosion in the ABS module. Test the fluid annually and perform a complete brake fluid flush every 2 to 3 years.

Power Steering Fluid

Modern advancements mean fewer fluids to check! The 2018 GMC Acadia utilizes an Electric Power Steering (EPS) rack. There is no hydraulic power steering pump, no hoses to leak, and absolutely no power steering fluid to check or change.

Windshield Washer Fluid

Any standard automotive windshield washer fluid will work perfectly. If you live in a region that experiences freezing temperatures, ensure you switch to a winter-grade fluid (usually rated to -20°F or lower) to prevent the fluid reservoir and lines from cracking due to ice expansion.

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Maintaining your 2018 GMC Acadia with the correct, OEM-specified fluids is the single best investment you can make in its longevity. Don't guess with universal fluids, and don't ignore your service intervals.

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