Gave my son a Mazda 5 and one day he and his friend borrowed some tools and the laneway to change the oil and filter.
After a couple of hours he comes in and asks “how much oil does this change take”? Of course I’m focused on work (worked from home since the early 80’s) and said I had no idea but check the dipstick and when it’s about halfway between the low and high marks, you’re in the zone.
About 30 minutes later he comes in and says that it’s staying around the same spot so it’s good. I decide to take a break and come out to see the boys (they’re in their 20’s, so men, I suppose) drive off down the street.
As the smoke starts to pour out of the exhaust, I call my boy, tell him to shut it off and pull it over.
Turns out they’ve drained the transmission and added God only knows how many litres of oil to the crankcase.
CAA towed the car to a friends garage where they drained the crankcase, refilled it and the transmission, test drove the car and pronounced it had suffered no ill consequences from the experience.
Not sure the boys share even my limited skill in the garage...
G