every 12000 miles
Yes, your fluids should be flushed every so often.
Urine because you can change the fluids often.
it doesn't.
Refer to owners manual, it will give you mileage frames on when to change fluids.
Every 2000 miles
Topping off fluids are often not advised on vehicles. Fluid chambers are so well sealed that the only fluids that are added are after a change of the fluids. If fluids need to be added at other times, it is the sign of a major problem and should be handled by an expert.
Follow the recommendations in your owners manual or change it every 5,000 miles.
every 10,000 miles
Probably every 5000 miles. Or 6 months.
It has a permanent filer that is changed when the fuel pump is replaced.
look in your owners manual but usually at 100,000 anymore.