Dear Sirs/Madam, I have a Saab convertible(year 2005-9/3).How often does

[absaq]

the synthetic oil have to be changed? The dealership state every 15,000 miles if leased (but every 5000 miles if you are going to buy out the lease.
It is the Mobil synthetic oil.

[aero viking]

the synthetic oil have to be changed? The dealership state every 15,000 miles if leased (but every 5000 miles if you are going to buy out the lease.
It is the Mobil synthetic oil.

do what your book says and any syntetic engine oil who fit the sae. and dot. classification read on the label if it says sae 5w-50 its fine