Under normal driving conditions you can easily go 7,000 miles between changes. If you drive mainly highway you can go 10,000 between changes. Also change the filter each time.
I've typically done 5000 or 6 months, but there are many case where you can go longer than that.
It should be done once a month
Change at 60,000 miles.
Generally every 30000 miles unless you have synthetic fluid, and the transfer case as well.
There are 2 answers that should be done together. Change your oil more often, and use a thicker oil.
Often times coupons for an oil change will include air filter as this is often done routinely with an oil change. A person should read the coupon to make sure though.
a testicular exam should be done once a month
Provided the grade and SAE of oil is that recommended by the car manufacturer and a filter change is done too, it should be OK.I don't recommend it personally. Many have had leaks after changing over. Also, it should never be used during break in period.
I heard that you should have ducts cleaned but I don't know how often. How often should furnace duct cleaning be done and how much does it cost?
there is not a set date to which it should be replaced, but if you flip it over it should not be cracked or frayed. if it is its time to get a new belt.
The brake system along with a complete safety inspection of the vehicle should be done at each oil change (aprox every 5K or once a year).
Usually the oil filter of the car is changed when the oil is changed. The oil change should be done on regular bases after like 3000-5000 miles or when the car is brought to the garage for a service.