Boy, this is one topic everybody has a different opinion on! Alot's been said on this and quite afew other threads. If you will allow me, I'll try and sum some of this up.

First, oil is the life blood of your engine. It cools, lubricates, removes dirt(that comes in with the air) & metal particles (that occur with all the moving, rubbing engine parts) from your engine. Ignore oil changes and the result is a seizedup engine (which my sister did to a BMW2002, Ouch!)

Filters filter(duh!) out the particles from the oil. When filters become clogged, there is a bypass that will allow the oil to continue to circulate, but now the oil will become thicker and thicker with contaminents, not lubricate properly, resulting in excess wear on the engine parts, overheating, etc, etc, etc...

Now you know what it's supposed to do. Forgive me, those of you who know more and can tell it in greater detail. I'm just trying to Keep It Simple, Stupid (K.I.S.S.)

BMW has oil change indicators that, on average, show an oil change at 15K miles. It varies based upon your driving habits. ie, with all my interstate miles, my indicator averages 20K miles. You have to decide, based on your driving habits (jackrabbit starts, Driving Miss Daisy, Mario Andretti wantabe, soccer mom, etc) and your environment (clean mountain air, smoggy commuter traffic, dusty desert, Sand Storms even!) what interval is YOUR comfort level. For desert desert, I'd be changing mine every 5K or after every sand storm, whichever comes first! As it is, I do mine every 10K since I don't trust the oil filter to be at peak efficiency beyond that (and it does get dusty out here in farmland Idaho during planting & harvest)

There are some of us that are skeptical of the new oil change intervals, now that the manufacturers are picking up the tab. It's been also pointed out that the oils and filters are much better than what they used to be. Again, it's subjective. You decide what you are comfortable with. Personnally, I think they put the indicators in so a certain gender would remember to at least ask, "What's this?" But that's just my opinion.

Hope this helped clarify the subject abit.

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Mark _______________________________
2001 X5 4.4i topaz blue/sand Sport, complete Dinan S2 , hitch, V1, tint, BSW Stage 1, Alpine INA-W910BT
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