Now wait, you stated you change every "5000Km", (that's roughly 3,106) because you do "around town short distances". You stated also, you change your Oil twice a year... you drive Less than 6500 miles per year and change your Oil twice?I do a lot of stop and start driving short distances and the oil is usually quite dark when it get changed. I look at it this way I pay CA$90 for an oil and filter change probably twice a year that may save me a ton of money in a few years time. My car is nearly six years old (I got it in Aug08) and I intend on running it into the ground and replacing it with a second hand 9-5 (the model due out this summer) when it does head off to that scrapyard in the sky.
It might pay for you to have an Oil analysis for 25 bucks......I think you'll see your throwing money away. I change every 7.5K and there are some that believe that's too soon. My car is an 03 105K+, does not burn or leak a drop.