I haven't had my Benz long enough to need my son (16 yo) to help fix anything....yet. He is learning however with his Caddy and Nissan, also he did a complete brake job, master cylinder down to the pads and shoes for the now defunct Plymouth. He went through "Dad's Driving School" as will my 13 yo daughter, basics of knowing how to check all the fluids, belts, etc. and knowing what they are called, as well as the SAFE way to change a tire. But back to the question, no, I wouldn't hesitate to have him help or do the complete repair himself.

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1991 300SE (my ride, 279,000 miles, looks almost new
1954 Cadillac (21 yo son's car, he bought when age 15)
1972 SeaBird 19 ft runabout (old but solid, slant six, Volvo sterndrive perfect condition, undergoing complete overhaul and refit)
1998 Toyota Rav4 (my sons daily driver when he is in the Continental US, PROUDLY serving in US Navy)