My car (2005 Blob STi) is going for a service next month, but Ive just checked the oil and its halfway between empty and full on the dipstick. I'd therefore like to put some more in to top it up until the service.

My questions are -:

1) What type of oil do I need? I'd like to put in the highest quality oil that I can, but oil that I will be able to find anywhere, not specialist stuff I'd have to order in.

2) How much should this oil cost roughly?

3) How much roughly would it take to fill the oil tank, now that the dipstick is currently on half full?

Would really appreciate some advice!!!!

Thanks a lot as always!

Chris.