Oil Change 04-07 Subaru WRX/STi DIY:
7.) Go ahead and start threading your oil pan plug back in. Get out your torque wrench and torque the plug to 44 N·m (4.5 kgf-m, 32.5 ft-lb). Once you have that torqued down grab your new oil filter. I usually grab one of the new bottles of oil and fill the oil filter up and lube up the threads. After filling the filter, carefully start threading it onto the oil filter spot. Once the filter turning gets hard, I give it an extra 1/2 to 2/3 turn to make it tight. You are now ready to start adding your new oil!
8.) With the oil drain plug and new oil filter added, go ahead and crack open a bottle of your new oil and start pouring it in. Make sure and remember that you are adding 4.8 US quarts of oil to your car. (This is what is required for the 04 STi, your car may differ. Make sure and check owners manual for correct amount required).
Once you have added one bottle, make a quick check under the car to make sure nothing is leaking, if all looks well, start adding the other bottles. Make sure that you are constantly checking underneath the car to make sure nothing is leaking.
9.) Once you have added your oil replace the oil cap and oil dipstick and start the car and again check to make sure nothing is leaking. If everything looks good, go ahead and let the car get to normal operating temperature. Once the car is at operating temperature stop the car and check the dip stick. If the dipstick is reading a little low add more as needed. As a good rule of thumb, add 4 and a half quarts and add as needed.I added 5 quarts to my car tonight and was right at the full line.