Originally Posted by Pretherius
So you've had bearing issues that you could definitively say were -not- due to maintenance habits?
I ask because, personally, I've purchased used cars that developed bearing issues. I'd be hard pressed to say for certain it wasn't because of maintenance habits.
I don't think your milk-dumping analogy is great because what you're talking about is purely wasteful. I'd liken it more to people who live an inactive lifestyle--there's a decent chance that they'll live to be elderly, but if they'd make the investment and exercise they would increase their odds. Similar to diligent vehicle maintenance--it's not a guarantee but it improves your odds, so it isn't a complete waste of money.
Fair enough question since I was not very clear in my comment, so let me simply clarify it by saying I've never had any *engine* bearing issues, nor valve issues, nor any internal engine problems of any
kind for that matter (I emphasize "engine" because wheel bearing issues are another issue).
You could be totally right that your purchased cars had engine bearing issues from maintenance problems. Note that I said I maintain to the letter of the manufacturer's intervals for all maintenance, whatever that may be. Many people do not even do that and I personally know many folks who've not changed the oil in their cars in 25k or more miles. THAT I do not advocate.
Again, I disagree about your last sentence because I do not think it improves your odds at all, and only buys that "good feeling" that you are going above and beyond. Contrary to belief, auto manufacturers do NOT want your engine to fail prematurely - it would kill their reputation in the market as well as their sales (not to mention open themselves to all kinds of litigation), so millions of miles of testing go into determining the optimal change intervals, which are then usually derated an additional 20% to 30% to give some overhead (or "padding," if you will) since most people are not so "to the letter" on the maintenance guide.
In other words, you could probably go even longer and still be fine, but again, I am not advocating anyone do that, only that you do what the company that engineered your engine - and know it far better than you - suggest you do.