Kinda depends Gilda. If those 300 miles involve starting it, driving 3 blocks, then shutting it off, then yeah, you probably need to change it that often. If it's mostly highway miles (not excessive stops/starts, and the car gets fully warmed up before you shut it off) then you're probably good waiting a bit longer.
You change the oil for two reasons: tiny little metal particles from engine wear get into the oil and cause faster engine wear. Changing the oil gets rid of them.
The other big reason is that over time the oil breaks down, you get water in it, etc. In short, your oil is no longer as oily as it was, so it doesn't lubricate as well.
While you won't get as many metal particles in the engine only driving 1800 miles as you would driving 3000 miles (assuming you're not starting it and switching it off excessively), your oil could still absorb water, especially if its humid where you live.
Here's how I look at it. I have a Honda with 300,000 miles on it, and the damn thing still starts every morning and still runs like a champ. I change the oil every 3000 miles/6 months religiously. It's 20 bucks that helps ensure I won't end up paying 1,500 bucks to replace the engine
