What are peoples' opinion on preventative maintenance?

[Boxtaboy]

Originally Posted by landrovered

It is not just Porsche doing this. Many other makes are reducing their service intervals as well.

I can understand them reducing service intervals as they introduce new cars, but retroactively recommend shorter intervals on their older cars? I wonder what prompted them to do that? My car hasn't changed since 2001...why is it that at first my owner's manual said I could wait till 15k before I change my oil, but now, I should do it at 12k intervals? Or fuel filter and plugs changed they say I should change at 60k miles, but now they say it should be done at 48k intervals.