The current research aims to study the surface roughness (Ra) analysis of stainless steel counterface type AISI-304 subjected to Treated Betelnut Fiber–Reinforced Polyester (T-BFRP) composites that are aged for a period of 3 years in different solutions with different kinematic viscosity. The test was conducted with a pin-on-disk wear test rig, which was designed and fabricated in-house according to ASTM G99-05, Standard Test Method for Wear Testing with a Pin-on-Disk Apparatus (Superseded). Different sliding distances (0–3.36 km) at a fixed applied normal load of 30 N subjected to a smooth stainless steel (60 HB) counterface at a sliding velocity of 2.83 m/s were used as the experimental parameters. Different orientations (O) of the betelnut fiber mats with respect to the sliding direction of the counterface were investigated, i.e., antiparallel (AP) and parallel (P) directions. The worn surface morphology was studied using a metallurgical microscope. Results revealed that the aged T-BFRP composite in a R134a solution demonstrated the lowest Ra values after the sliding wear test and after the counterface was cleaned. This result is due to the lowest absorption rate (i.e., highest kinematic viscosity) incurred by the aged AP and P test specimens as compared to the other types of aging solutions. As such, the improvement in Ra values of the samples aged in R134a solution were 87.8 and 99.9 % for the aged AP and P test samples, respectively, as compared to the aged neat polyester (NP) samples. It was also noted that the fibers had low absorption rates when they were aged in solutions with high kinematic viscosity; in other words, the aged T-BFRP composite demonstrated the lowest absorption rate (≈0.0085 %) when it was aged in the R134a solution. Aged NP did not show any remarkable absorption into the test samples mainly because of the absence of fibers. All in all, this work reveals a possible method that can be used to lower the damage on abrasiveness to processing equipment by means of aging the composite in various solutions with different kinematic viscosities.