Thank you PiB that is the type of information I am fishing for, but I would like more.
Additional information, my grand niece is totally ignorant of mechanicals and has been conned twice. The first time, the charge warning light came on and I looked and saw that the fan belt was missing, so I sent her to have it replaced. The garage said no, you need a new alternator, so she forked out almost ฿10,000 for a new alternator. The second time , the brake warning light came on and I spotted that the brake fluid level was low. While I was away looking for brake fluid, she took the car to a garage which replaced all the discs and pads but not the fluid. I replaced the fluid for her, it was filthy and had obviously been in the system since the car was new. She has learned to trust me more than dealers and garages, hence the reason I an looking for information on a subject that I,as yet, know very little about.
Please keep relevant comments coming.