2004 Chevy Blazer oil filter location?

Drive onto ramps. Get out creeper and slide under the front bumper. Look up at the plastic panel that keeps crud from hitting the radiator and A/C condenser. You will find the oil filter access panel held up by a single 1/4 turn fastener. Drop the panel down and the filter is on the adapter about 3" up from the panel.

When you go to get a new filter there are two that will fit your truck. One is listed for a two wheel drive and one for 4X4. I use the larger filter for a 2WD since it fits fine and has more filter area. The 4X4 one is meant for the older S series that have a tight filter location inside the fender under the hood.