1998 Harley-Davidson Motorcycle Oil
AMSOIL synthetic oil recommendations for every 1998 Harley-Davidson model. Choose your model below for engine capacity, oil change interval, and AMSOIL part numbers.
1998 Harley-Davidson Oil Recommendations
Every 1998 Harley-Davidson Big Twin on this page is powered by the Evolution V-Twin, the engine that defined the modern Harley era from 1984 through 1998. Evos run cooler than later Twin Cams but still benefit enormously from synthetic oil because of their long highway-cruise tendencies and tendency toward varnish buildup with conventional oils. AMSOIL 20W-50 100% Synthetic V-Twin Motorcycle Oil is the recommendation across 1998 FL, FX, FXR, and Softail models, while Sportster XL/XLH platforms have their own listed grades.
AMSOIL synthetic V-twin oil naturally resists oxidation and deposit formation, two failure modes the Evo platform is especially prone to after long highway runs. Combined with extended drain intervals, it is a measurable upgrade over the conventional oils most 1998 Evo owners default to. Tap any model below for engine displacement, oil capacity, AMSOIL part numbers, and the exact Harley oil change interval.