I just bought a 2002 subaru wrx automatic (good price so i had no choice) with 136k stock runs great! but when i first start the car in the morning i hear a little knocking sound, after about 10-15 minutes of driving this sound eventually lowers to the point that i can barely hear it but it is still present! It also has a small transmission leak, about how much would cost me to fix this leak? The car has a lot of miles and i would like to not spend too much on it. But I am thinking it would be a good idea to take it in for a check up and if there are problems with the car i will just fix the most important ones.