Some of the B listed roads in Scotland are single track roads. There are signs near to wider sections "Passing Place" where you should pull in if someone wants to pass but more importantly to let on coming drivers through. The general rule is whoever is nearest the passing place stops. So mind your manners & always give the driver a cheery wave.
Just a quick word of warning - if you have been out on a Saturday night, and are staying further than a few minutes walk away from the centre, I would advise calling a cab in advance or booking one to pick you up. In Oban on a Saturday night, it can get very busy and everyone pours out of the pubs etc all wanting a taxi at the same time.
There is only one taxi rank in Oban (at the train station) and everyone ends up hanging around this waiting - it is a complete nightmare!! Especially if it is mid-winter and pouring with rain - I am talking from experience here - boxing day 2004!!
You are at the mercy of the island and ocean unless they get this cruise liner serviced.....luckily it was not long.