Triumph Bonneville Bobber 2018 Owner's Handbook Manual page 133

Fluids and Lubricants
Bearings and Pivots
Brake Fluid
Coolant
Drive Chain
Engine Oil
Bonneville Speedmaster
Grease to NLGI 2 specification
DOT 4 brake fluid
Triumph HD4X Hybrid OAT coolant (pre-mixed)
Chain spray suitable for XW-ring chains
Semi or fully synthetic 10W/40 or 10W/50 motorcycle
engine oil which meets specification API SH (or
higher) and JASO MA, such as Castrol Power 1 Racing
4T 10W-40 (fully synthetic) engine oil, sold as Castrol
Power RS Racing 4T 10W-40 (fully synthetic) in some
countries.
Specifications
133