Change oil pan gasket 98 olds intrigue?
Do you mean "how to change the oil pan gasket?", or "should I change the oil pan gasket?". I assume you have a leak around the pan and need to change the gasket. If so, be sure that it is indeed a gasket leak by cleaning off the engine and pan and checking it again after an hour of driving. The 3.5L are notorious for using oil (about 1 qt every 1000 mi is considered average). Don't just assume this oil is leaking out.
To change the gasket is a lot of labor but is fairly straightforward. Drain the oil, remove the dozen or so bolts from the pan, and pry it off being as careful as possible to not gouge the block or bend the pan lip. Remove the old gasket with a scraper, again being careful to not scratch up the block or the pan. Install a new gasket (they come in a kit with the proper sealant, I believe (never done an Olds myself)). Bolt it back on and retorque the bolts to the level and in the order specified in the kit. The pan on the 3.5L includes the oil filter carrier, which may need replacement if it is worn. These can leak as well.