Twin Cam
2010 Harley-Davidson FLSTFB Fat Boy Lo Oil
AMSOIL synthetic oil recommendations for the 2010 FLSTFB Fat Boy Lo.
Why AMSOIL Is the Best Synthetic Oil for the 2010 FLSTFB Fat Boy Lo
This guide covers the 2010 Harley-Davidson FLSTFB Fat Boy Lo specifically. AMSOIL synthetic oil recommendations match the engine code, displacement, and oil capacity that shipped on this exact variant, so you order the right viscosity and the right number of quarts the first time.
Twin Cam-powered Harleys generate enough cylinder heat to thin conventional oils during long touring days. AMSOIL synthetic V-twin oil holds its film strength where stock dino oil falls apart.
Twin Cam crankcases share oil between engine, transmission, and primary - so the same fluid that protects pistons also protects gears and clutch packs. AMSOIL synthetic 20W-50 V-Twin oil maintains its film thickness where conventional oils get sheared down by the gearbox, which is exactly why long-haul Twin Cam owners report smoother shifting and quieter primaries on synthetic.
Frequently Asked Questions
How much oil does a 2010 Fat Boy Lo take?
The 2010 Harley-Davidson FLSTFB Fat Boy Lo holds approximately 3 to 3.5 quarts of engine oil with a filter change. Always confirm via the owner's manual and check the level on the dipstick after refill.
What is the best oil for a Fat Boy Lo?
AMSOIL 20W-50 100% Synthetic V-Twin Motorcycle Oil is the recommended choice for the 2010 Fat Boy Lo. It outperforms Harley-Davidson Screamin' Eagle SYN3 by 6X in independent shear-stability testing and protects the integrated transmission and primary in the same drain interval.
How do I change the oil on a Fat Boy Lo?
Warm the engine for 5 minutes, drain the engine sump via the lower drain plug, replace the oil filter (AMSOIL Ea Motorcycle Filter), refill with the manufacturer-specified amount of AMSOIL 20W-50 V-Twin Synthetic, then run the engine for 30 seconds, let it sit 5 minutes, and check the level via the dipstick with the bike upright on a level surface.
What is the oil change interval for a 2010 Fat Boy Lo?
Harley-Davidson recommends 5,000-mile engine oil change intervals with conventional oil. AMSOIL synthetic V-twin oil's superior shear stability and oxidation resistance lets you confidently follow that interval, or use AMSOIL's extended-drain guidance for severe service. Transmission and primary fluids are typically changed at every second and third engine oil change respectively.
How often should I change the primary fluid in a Fat Boy Lo?
AMSOIL recommends changing the primary chaincase fluid every third engine oil change. The Fat Boy Lo's clutch pack runs in the same fluid, and AMSOIL synthetic primary fluid maintains consistent friction characteristics for smoother clutch engagement throughout the interval.
