By the time the 2002 model year rolled around, the Chevy Blazer had run its course and it was time for something new, so Chevy released the Trailblazer as the replacement for the four-door Blazer models. The two-door Blazer continued strong through the 2005 model year, to keep two-door SUV buffs happy. Changing the 2002 Trailblazer's oil is fairly straightforward, thanks to the simple design of its 4.2-liter, inline-six engine.
Start the engine and let it idle until it reaches its normal operating temperature. Park the Trailblazer on a flat surface and turn the engine off. Open the hood and unscrew the oil filler cap from the top of the engine. Wedge wheel chocks behind the rear wheels. Position a floor jack under the center of the front suspension crossmember and lift the front of the SUV. Set jack stands under the frame, just to the rear of the front wheels. Lower the Trailblazer until only the jack stands support its weight.
Crawl under the vehicle and find the oil pan drain plug -- the small bolt near the bottom of the oil pan -- and set a drain pan directly under it. Loosen the drain plug with a combination wrench, then remove the plug by hand, using a thick shop cloth to protect your hand from the hot oil. Allow the oil to drain into the drain pan until the flow of oil slows to only a few drips. Wipe the drain plug off with a clean, lint-free cloth, reinstall it and torque it to 19 foot-pounds, using a torque wrench and socket. Wipe any residual oil from around the plug with a shop cloth.
Find the oil filter -- the large, metal canister -- on the front, passenger side of the engine, and set the drain pan under it. Loosen the oil filter, using an oil filter wrench, until oil starts flowing from the top of the filter. Wait for the flow of oil to stop, then remove the filter the rest of the way by hand and upend it in the drain pan. Clean the oil filter mounting boss with a clean, lint-free cloth and verify that the old O-ring came off with the old filter. If it did not, pull the O-ring off the mounting boss.
Coat the new oil filter's O-ring with new 5W-30 engine oil, with your finger, and hand-thread it onto the mounting boss. Tighten the filter to 22 foot-pounds, using a torque wrench and an oil filter cup, then turn it an additional 150 degrees to seat it on the boss.
Lift the Trailblazer off of the jack stands and lower it to the ground. Insert a funnel in the oil filler hole on top of the engine, then pour seven quarts of new, 5W-30 engine oil into the engine. Wait for about two minutes for the oil to settle, then remove the oil dipstick, wipe it clean with a clean, lint-free cloth, then reinsert it. Remove the dipstick again and verify that the oil level is slightly above the "F" line. Add more oil if needed.
Remove the funnel, close the oil filler cap and start the engine. Allow it to run for about two minutes, then shut it off. Wait five minute for the oil to settle, then recheck the oil level. The level should be right on the "F" line. Add more oil if needed. Take the old engine oil to an aut parts store for recycling.
Reset the "Change Eng Oil" light by turning the ignition key to the "Run" position without starting the engine, then fully pressing and releasing the accelerator pedal three times within five seconds. The "Change Eng Oil" light will flash for five seconds if you correctly performed the reset procedure. If the light does not flash, shut the ignition off and repeat this step.
