2018 Harley-Davidson FLHRXS Road King Special — Maintenance & Ownership Guide
Routine Maintenance
Key maintenance tasks to keep your 2018 Harley-Davidson FLHRXS Road King Special running reliably.
Engine Oil
Requires approx 5.0 quarts of 20W-50; intervals are every 5,000 miles, though many owners prefer 2,500-3,000 miles due to heat.
Primary & Transmission Fluid
Separate cavities requiring specific lubricants (Formulated for Primary and Transmission); critical to monitor levels due to known migration issues.
Hydraulic Clutch Fluid
Uses DOT 4 fluid; Harley recommends flushing every 2 years to prevent moisture buildup and slave cylinder failure.
Common Wear Items
Parts that wear over time on the 2018 Harley-Davidson FLHRXS Road King Special and should be inspected regularly.
Brake Pads
Heavy touring bike (800+ lbs) wears through pads quickly, especially the rear if using linked braking heavily.
Tires
The 19-inch front Turbine wheel uses a lower profile tire that can be prone to cupping if pressure is not maintained strictly.
Popular Upgrades
The most popular aftermarket upgrades for the 2018 Harley-Davidson FLHRXS Road King Special.
Stage II Cam Kit
The 107 M8 responds exceptionally well to torque-focused cams, waking up the mid-range for better highway passing.
LED Lighting
While it has a large nacelle, the stock halogen bulb is often replaced with a Daymaker LED for better night visibility.
Seat
The stock 'Special' seat is low-profile for style but can be uncomfortable for long-distance touring; common swap for Saddlemen or Mustang.
Common Replacement Parts
Parts that commonly need replacing on the 2018 Harley-Davidson FLHRXS Road King Special.
Battery
High-compression 107ci engine requires a strong cold cranking amp (CCA) battery (OEM 66010-97D) to avoid starting strain.
Spark Plugs
Dual-plug head design (4 plugs total); replacement is recommended every 30,000 miles.
Used Buying Inspection Checklist
What to look for when buying a used 2018 Harley-Davidson FLHRXS Road King Special.
Oil Pump / Sumping Check
Verify if the oil pump has been upgraded to the 2020+ version (Part #62400247) to prevent catastrophic 'sumping' failure.
Primary Vent Kit
Check for the presence of a vent tube on the inner primary (TSB M1492) which fixes transmission-to-primary fluid transfer.
Compensator Noise
Listen for a loud 'clunk' or 'bang' on startup or shutdown, which indicates a failing or weak compensator sprocket.
Hydraulic Clutch Recall
Check service records for the 2018 clutch actuator recall (Harley Recall 0173) to ensure the secondary actuator was replaced.
Your cart is empty