Arrived on site to perform fall tune up 2 17 year old units. Cycled both units on. Filter where extremely dirty from lack of filter change out and are very in need of replacement. Found black flex ducting used as it’s old but okay at this time. Both blower assembly are dirty from lack of filter change out in the 17 years of life. Both motors are leaking oil from over working. Could face issues in future. Both secondary motor controls are weak and out of range and will fail soon in future. Both inducer motors are in range just working high. All safety switches are operational. Both drain lines are dirty from dirt entering system. Could risk over flow in attic. No safety over flow switches. Recommend adding some. No protection on unit recommend adding surge pro To systems. Due to air quality and filtration would recommend adding a filter reck to upgrade filter and for it to be replaced just once a years as filters are not getting switched out enough or as needed. Cycled both systems.