63 year old disabled out of date mechanic just trying to help my grandkids with there 1st cars

 

Welcome to the forum

Well depending on which model you are going to at least need a good diagnostic scanning device (NO BLUE TOOTH) and brush up on your OBDII diagnostic information as well how to trouble shoot an OBDII Mazda ECU controlled vehicle.
Other then that the running gear for general purposes are still with in OLD school Mechanic's abilities for service and trouble shooting.

Honestly your age and most disabilities are not a factor if you have years of auto mechanical service behind you...