Oil filter

This is for a 1993 Bonneville 6cyl 4dr

I recently talked to a friend that has NEVER had his oil officially changed. He told me all he does is top off the oil then it runs a little low and only changes the filter. (say the filter gets changed every 3 months)

I want to know if this is good practice, and also I would like to start changing the oil and filter myself, problem is I have no idea how to do that.

If someone could direct me to a link or just describe in detail it'd be much appreciated.

It is not a good practice. Contaminants will settle into the oil pan.. there is no chance replacing the filter will remove them from there. It is easy to change the oil. Jack the car up, put a jack stand under it in a good place in case the jack fails. put an oil pan underneath to catch the oil. (remember that the oil may shoot out a little ways away from the oil pan when the bolt is removed. The bolt on my 1996 is 15 Metric I believe. Remove it to drain the oil. Once the oil is mostly drained or draining slowly, remove the old oil filter. (both the bolt and filter have regular threads.. meaning you turn counter clockwise to remove them). Once it all stops draining, put a little oil in the new filter before you install it... sometimes helps with removal later if you take your finger and apply a thin coat to the rubber seal also. If you have strong hands, you can tighten the filter by hand real well. Do not overtighten with a wrench. Put the oil plug bolt back in.. lower the car and put in close to the prescribed amount of oil (4.5 qts in the case of my 3800 if I remember right off the top of my head.. so I put in 3.5 to 4.. as measured by the marks on the side of the 5 qt container...) Then I check the dipstick and add as needed to top it off. Run the car a minute or two so the filter gets its full share.. then turn it off and check the dipstick again and top off as needed. Do not overfill. It really is not hard and does not take very long. Check your owners manual for the filter part number and how much and what kind of oil to buy. You'll do fine.