OK, but it is not just about doing what BMW says. It is about looking at people who have already done what BMW recommends and the results they have had. Like I said, I have seen the photos of BMW engines torn apart at 100,000 miles where the owners strictly followed the 15,000 oil intervals and was amazed at the good condition of the motor. Once again, I never heard of any wear related failures by following in the BMW service intervals with OE oil and filters.

Also, I have never heard of any engine issues related to owners following 100,000 mile OE plug change intervals.

Agree to disagree though.

I dont rely on a camera and pictures or Heresay to check tolerances. BMW is in the buisness of making money and saving money, but not for you. Changing plugs @ 50k vs. 100k isnt about preventative maintainence. Its about performance and efficiency.
Without writing a thesis, changing your oil is about what people have done for a long time for reason, not some new-fangled BMW propaganda, and tree hugger's far reaching effects of a quest to save the planet. Its cheap insurance that cuts the wear factor significantly. If BMW took care of everything for you this forum wouldnt exist.

Well, since you brough it up have you checked the tolerances personally? Do you have any data for us on BMW engines that saw 15,000 mile intervals compared to say 5,000 or 10,000? What are you basing your info on? Hearsay, perhaps?

Once again, If I snuck into your garage and changed your plugs earlier than recommended, I highly doubt you would actually notice any increases in performance of efficeincy.

As others have said many times on this forum, oil has changed dramatically over the years. especially in the last 10 or 20. It is much better than when people were changing oil every 3,000 miles.

I don't expect BMW to take care of everything for me and I know they (as with any company) are interested in maximising profits, but I also don't think they chose intervals that will lead to their vehicles falling apart or failing. At the end of the day, they want their products to be reliable.

To each his own though. I completely understand if performing this routine maintenance earlier than what BMW recommends makes you feel better, but I would like to see that data that shows it actually makes your engine last longer.

BMW engine isnt made of unobtanium. I'm sure BMW has some sort of algorithm that tells them: if they change ur oil for the first 50k, you buy an extended warranty or they certify it CPO when u trade it in, the engine will not have an oil related failure by 100k. Then it is not there responsibility and they don't care. Don't believe everything daddy BMW tells you, that's like the police policing the police. BMW goal is to get a vehicle thru to 100k while maximizing profits, as well as marketing free maintanence and availability of CPO.
Like I said, NO oil change till 100k would probably be fine. Cylinder wear, bearing wear, valve guide wear, lifter wear, cam lobe wear(which affects duration and lift), blah blah, not to mention internal corrosion is NOT going to be "MINIMIZED" with extended intervals.
Why don't you show me data that says it DOESN'T make it last longer?
Tell me why you change your brake fluid? Cuz it breaks down and gets dirty?
And we're not talking about vehicles falling apart and breaking down, we are taliking oil and plugs.

"Once again, If I snuck into your garage and changed your plugs earlier than recommended, I highly doubt you would actually notice any increases in performance of efficeincy"

If I did, would you call me a liar, and rebutt my math? (BTW performance and efficiency are hardly synonomous)

Do what you do-I call it cheap insurance.

Your analogy suggests that the engineers who design the vehicle work for the same marketing department that sets the warranty terms. Not true. The vehicle is designed for a global market, and uses the same engines (with some certification differences for emissions). Warranties offered by the various regional sales and marketing companies.

Prepaid maintenance is only in the US (and Canada, and select other countries). It is offered to overcome consumer fear of dealer prices. It never entered into the vehicle design process IMO.

Throwing brake fluid into the conversation is a little misleading; it is clearly hygroscopic, and BMW recommend changing it every two years. The reasons for changing it (and the risks of not doing so) are clearly documented.

I replaced the plugs in my X5 4.6is at 105K miles. They looked to be in fine shape. And the new ones had no noticeable effect on performance whatsoever. The originals were BOSCH in my engine and I replaced them with the NGK listed above. I would bet these plugs are good for 100K miles as well because the factory plugs were marked with the same BOSCH PN and then also had a BMW logo stamped on them. Knowing a little bit about how production control works, I find it hard to believe that BOSCH or NGK would make a special BMW-spec plug and still stamp the same PN on it. I think the 3X price is pure BMW profit margin on parts. That said, I may still replace these in 60K miles or so if I still have this vehicle and it is still in good operating condition. I hope to own it then, but my track record is not very good in that dept. so you never know.

I just picked up a 89K mile 740i that still has the original plugs. It runs great and has been getting 25mpg in mixed highway and city driving and 27-28 on the highway. So I'm thinking those plugs are working rather well. I will replace them in about a year when the car has 100K on it. I see no reason to change them early. I will probably use the BOSCH plugs this time since BMW dealers stopped using NGK. That may be for a reason - don't matter to me, both are about the same cost. I won't buy the BMW branded plugs.

I do not agree that 100K oil change interval would be fine. A motor might make it to 100K miles without an oil change, or it may not - hard to say. But it would certainly be trashed by that point either way. Once the oil breaks down the wear is going to skyrocket.

And there really isn't much benefit to changing oil before it breaks down. One can argue how long that will take in a given engine with a given oil formulation, but only oil analysis from a lab will really tell you the truth. I have no reason to doubt BMW's analysis in this area. That said, 15K feels a bit longish to me. Audi recommends 10K for example using similar oil formulations and very similar engines. On my Corvette it works out to aprox 10K as well which is determined by a computer algorithm analyzing driving patterns - more steadystate driving extends the interval for example.

So personally I follow a 10K schedule on my BMW's, which works out to about once a year. That seems about right to me.

But 10K or 15K I don't think will make a huge difference. These BMW engines should last beyond 200K miles if properly cared for. The rest of the vehicle is less likely to make it that long before causing too many problems to make it worthwhile to keep driving it.

Plus you never know what is going to happen. I bought a 2003 Mazda for my wife and maintained it very well - typically changing oil using standard non synth every 5-7K miles. The radiator blew at 120K miles and the motor overheated and blew a headgasket and likely warped the head. So I ended up replacing the motor with a take-out from a Japanese market car with 40K miles on it. Could that engine have gone to 200K? Probably so. But it's life was cut short due to factors completely unrelated to oil and component wear. With the new engine I decided I would run synth and stick to the same 10K change intervals I use on my BMW's. which works out to twice a year on that car. Fingers crossed that something else doesn't take it out prematurely. But even if it does, the replacement motor was only $1K. Too bad there is no such supply of cheap replacement motors for our BMW's, eh?

i-want-in,

I don't think there is anything wrong with changing oil, filters, plugs or any maintenance items for that matter before BMW's recommended intervals. If that is what you like and if it makes you feel better, then by all means do so. I just think that on the flip side, there is the arguement that doing it significantly before the manufacturers recommendations is somewhat of a waste of money as there is no proof that it actually extends engine life.

How long has BMW had the 15,000 mile oil intervals now, 10 years or so? In that time period there have been many engines run hundreds of thousands of miles following these recommendations and so far there have not been any large scale engine failures from doing so. BMW seems to think that 15,000 max intervals wont harm your engine. I happen to agree with them and I would say my proof would be a decade of success with 15,000 mile changes. The burden of proof would be on you to show us otherwise.

what is the torque spec for the plugs? I am interested in doing this but scared of over torquing it

You're preaching to the choir about maintenance and staying away from the dealership, so why are you taking this defensive stance with me?