Harley-Davidson Softail Slim 107 (FLSL) — OEM Fluid, Tire Pressure & Maintenance Specs
1,746cc Air/Oil-Cooled Dual-Counterbalanced 45° V-Twin Milwaukee-Eight 107 · Source: Harley-Davidson Softail Slim 107 (FLSL) (2018–2021) Official Owner’s Manual Maintenance Specifications
According to the Harley-Davidson Softail Slim 107 (FLSL) (2018–2021) Official Owner’s Manual Maintenance Specifications, the 2018–2021 Harley-Davidson Softail Slim 107 (FLSL) (chassis FLSL) requires 4.3 L (4.54 US qt) of SAE 20W-50 (JASO MA2, Screamin’ Eagle SYN3 20W-50 / H-D 360 20W-50) engine oil for a drain-only change and 4.7 L (4.97 US qt) with filter service (HD 62700296 / 62700297 (HF171C)). Standard solo cold tire pressure is 248 kPa / 2.48 bar / 36 PSI front (130/90B16 73H) and 276 kPa / 2.76 bar / 40 PSI rear (150/80B16 77H), paired with 4× HD 6R10 (31600012 Dual-Plug M8) spark plug(s) and a YTX20HL-BS / HD 65989-97E battery.
Drain only: 4.3 L (4.54 US qt)
R 276 kPa (2.76 bar)
Est. Range: ~352 km (219 mi)
1. Engine Lubrication, Filter & Clutch Specifications
| Clutch Architecture | Wet Multi-Plate Manual Clutch NEVER use JASO MB |
|---|---|
| Recommended Viscosity & Grade | SAE 20W-50 · JASO MA2 · Screamin’ Eagle SYN3 20W-50 / H-D 360 20W-50 |
| Oil Volume (Drain / With Filter / Overhaul) |
• Drain only: 4.3 L (4.54 US qt) • With filter/strainer: 4.7 L (4.97 US qt) • Complete dry overhaul: 5.2 L (5.49 US qt) |
| OEM Oil Filter Code & Type | HD 62700296 / 62700297 (HF171C) |
| Correct Oil Level Check Method | At full operating temperature resting ON THE SIDESTAND (Jiffy Stand); thread dipstick in to read |
| Oil Drain Bolt Torque | 24 N·m (17.7 lb-ft / 2.45 kgf·m) — Use fresh crush washer |
| Primary Chaincase Fluid | 1065 ml (1.06 L) — H-D Formula+ Primary & Clutch Fluid (900–1,065 ml wet refill) |
| Separate Transmission / Gearbox Oil | 828 ml (0.83 L) — H-D Formula+ or Heavy Synthetic Gear Oil 80W-140 (828 ml / 28 oz) |
2. Cold Tire Pressures, Wheels, Ignition & Drivetrain
| Front / Rear OEM Tire Sizes | Front: 130/90B16 73H · Rear: 150/80B16 77H (Tube-Type Spoke Rim) |
|---|---|
| Cold Tire Pressure — Solo Riding |
Front: 248 kPa / 2.48 bar / 36 PSI Rear: 276 kPa / 2.76 bar / 40 PSI |
| Cold Tire Pressure — 2-Up / Loaded Touring |
Front: 248 kPa / 2.48 bar / 36 PSI Rear: 290 kPa / 2.90 bar / 42 PSI |
| OEM Spark Plug & Quantity | HD 6R10 (31600012 Dual-Plug M8) × 4 (Gap: 0.8–0.9 mm) |
| OEM Battery Code & Rating | YTX20HL-BS / HD 65989-97E (12V 18.0Ah Heavy-Duty AGM) |
| Final Drive Maintenance | Carbon/Aramid Reinforced Secondary Belt — Inspect belt deflection and pulley debris |
| Brake Fluid & Coolant | DOT 4 · Air/Oil-Cooled Engine (No liquid coolant) |
3. Ergonomics, Range & Scheduled Service Intervals
| Displacement · Max Power · Peak Torque | 1746 cc · 86 hp @ 5,020 rpm · 145 N·m (106.9 lb-ft) @ 3,000 rpm |
|---|---|
| Seat Height & Wet Curb Weight | 660 mm (26.0 in) · 304 kg (670 lbs) |
| Fuel Tank & Est. Real-World Range | 18.9 L (5.0 US gal) · ~18.6 km/L → ~352 km (219 mi) |
| OEM Scheduled Maintenance Intervals |
• First Break-In: 1,600 km • Engine Oil / Filter: 8,000 km / 8,000 km • Air Filter / Spark Plug: 24,000 km / 48,000 km • Valve Clearance Check: 48,000 km |
4. Generation Cutoffs & Real-World Wrenching Gotchas
Model-Year & Chassis Generation Notes
Built for 2018–2021 with an ultra-low 660 mm seat height, Hollywood crossbar handlebars, half-moon footboards, and 16-inch laced bobber wheels on the M8 107 Softail frame.
Oil & Clutch Mechanical Engineering Note
Because the slammed FLSL sits low over speed bumps, inspect the under-slung M8 107 sump pan at every 8,000 km 3-Hole SAE 20W-50 oil service.