what viscosity oil is recommended for my 2005 Subaru wrx sti

most cars unless your in very hot temp use 5w30 is recommended for most cars

Synthetic 5W30 or 10W30 is required on these bad ## cars.

Best bet is to check the manual, but personally, l use 5w-30 year round in my 07 WRX. Only time l would go higher vis than that is extended use in high temps, or if your car sees a lot of track use

If you look on the oil fill cap for the car, it has it printed on the cap what oil as well as how much to put in. If the caps gone or the printing is worn off, then all you need to do is call either a Napa auto parts or a Shuck is parts store. They will have the information on the computer for your car is engine and year.

Mobil 1 synthetic 5W-30 thats all l use

It should say in your manual. Mobil 1 is widely known to burn in our motors.