Due to marital status, children and age, I resorted to having shops change the oil in my '89 Toy 4X4. Decided that my time with the family was more important that the hassle of the oil, filter, pan and disposal process.
I may have learned the hard way, the old addage that if you want it done the right way......
I caught a shop once being lazy. They didn't change the filter. Who knows if they changed the oil.
But the biggest leason I am sad to say that I learned today. If you do not have an analog oil gauge, make certain that your oil light illuminates when you turn the key on before the vehicle starts. If you oil light never lights up, check that wire where it plugs into the sending unit. On my truck the oil sending unit is located beside the oil filter. It can best be reached through the passenger wheel well.
I think that the last time I had my oil changed, they bumped this wire loose. And I think that I recently lost my oil pump. My engine started making some loud noise. I removed the oil filter and cut it open. The paper filament had collapsed and was filled with fine shavings of metal. I also had two burned (and dry) valves. I need a new engine.
It is a good habit to check that your oil light works. It is also a good habit to cut open your oil filter every time you change your oil just to check for particles. I have also just learned that there are services which will test your used oil for about $7.00. They will tell you how many PPM of different particles are in your oil.