Blue - Loctite 243 threadlocker is a medium strength, general purpose adhesive, suitable for securing and sealing nuts, bolts and studs to prevent loosening, this adhesive has a tolerance to slight contamination by industrial oils and cutting fluids.
Red - LOCTITE® 263™ Primerless, Oil Tolerant High Strength Red Threadlocker is designed for the permanent locking and sealing of threaded fasteners. LOCTITE 263 is particularly suited for heavy duty applications such as studs into motor housings, nuts onto studs in pump housings and other fasteners where high strength is required.
Green -Top Pick Loctite 680 is a high strength, high viscosity room temperature curing adhesive used to join fitted cylindrical parts. It fixtures in 10 minutes and provides a shear strength of 4,000 psi. Capable of filling diametral gaps up to 0.015 in. (0.38 mm). Loctite 680 allows relaxed machining tolerances, and replaces clamp rings, set screws, and snap rings. Gives best resistance to dynamic, axial and radial loads. Recommended for retaining shafts, gears, pulleys and similar cylindrical parts.