The 2018 Duramax-equipped Chevy Silverado/Sierra uses Dexron VI automatic transmission fluid (ATF) for the power steering system.
For Ford or non-GM viewers, it’s worth noting that GM’s hydraulic power steering systems adopted Dexron VI ATF in the mid-2010s. In the 2018 Duramax trucks—located in Silverado and Sierra models—the steering system relies on Dexron VI ATF to provide the necessary viscosity, lubrication, and anti-foaming properties. Using the correct fluid helps maintain steering feel and component longevity, while using the wrong type can lead to performance issues or potential damage over time.
Fluid Type and Compatibility
Dexron VI ATF is the recommended and widely accepted fluid for the Duramax hydraulic power steering system. This includes GM's own Dexron VI-branded products or GM Original Equipment (GM OE) Power Steering Fluid labeled as Dexron VI. The key is to use a fluid that meets the Dexron VI specification rather than older Dexron II/III fluids or ATFs that specify incompatible formulations.
- Use Dexron VI ATF (or GM OE Dexron VI Power Steering Fluid) for the Duramax power steering system.
- Avoid mixing different ATF specifications (e.g., Dexron II/III, ATF+4) unless explicitly approved by GM for your VIN.
- Look for labeling that indicates Dexron VI compliance on the bottle or product data sheet.
Using the correct Dexron VI ATF helps ensure proper seal compatibility, lubrication, and anti-foaming performance. Incorrect fluids can lead to noisy operation, reduced steering feel, or long-term damage to the power steering pump and hoses.
Where to Buy and How to Verify
Before purchasing, confirm your vehicle’s exact requirements by consulting the owner's manual or a GM service bulletin. In practice, most 2018 Duramax Silverado/Sierra models use Dexron VI ATF for the power steering system, but VIN-specific guidance can help in edge cases.
- GM-approved Dexron VI ATF sold as GM Original Equipment (GM OE) or Dexron VI-branded ATF.
- Major-brand Dexron VI ATF products that explicitly state Dexron VI compatibility and GM approval.
- Power Steering Fluid sold specifically for GM vehicles, labeled Dexron VI or Dexron VI Power Steering Fluid.
If you’re unsure, ask a dealer or a certified technician to verify the correct fluid for your exact truck configuration. Improper fluid selection can complicate maintenance and potentially affect warranty coverage.
Maintenance Tips for the Duramax Power Steering System
Here are practical guidelines to keep the Duramax power steering system performing well, assuming you’re using the correct Dexron VI ATF.
- Keep the reservoir level between the marked minimum and maximum when the engine is cold; if it’s low, top it off with Dexron VI ATF only.
- Avoid mixing fluids from different specifications; if a flush is required, perform a proper Dexron VI ATF flush rather than partial top-offs with other ATFs.
- Watch for signs of trouble: whining, stiffness, leaks, or erratic steering response warrant inspection and possible fluid replacement.
- Replace or flush the power steering fluid only as needed or per GM/service guidance; many vehicles don’t require a regular interval, but severe contamination or noise is a good reason to service.
When in doubt, consult a qualified technician or a Chevrolet/GMC service center. They can confirm the exact Dexron VI ATF specification for your VIN and provide proper service recommendations.
Summary
For a 2018 Duramax-powered Chevy Silverado or GMC Sierra, the recommended power steering fluid is Dexron VI ATF (GM Dexron VI or GM OE Power Steering Fluid). Use the correct Dexron VI fluid, avoid cross-spec fluids, and follow vehicle-specific guidance from the owner’s manual or dealership service teams. Regular checks of the reservoir and attention to unusual steering behavior will help maintain system reliability over time.
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