Is My Car Mechanic Giving Me Bad Advice?

What Engine Oil Weight do I use in my 1999 Chevy Suburban? Why does my 1996 Silverado drop out of Overdrive? Why does my 2012 Jeep get hot when I drive it hard? Why do my Chevy Trax Cooling Fans stay running? Do I really need ball joints on my Trailblazer? How do I remove stuck Spark Plug Boots? How do I pass a Smog Test in California? Does my Ram Truck have a bad cam or bad oil filter? Does my Toyota Tacoma have bad Catalytic Convertors?