I only discovered this interesting discussion now.
Most Grenadier owners are over 50! Old blokes like me (me: 67 today, yes today, no congrats needed). We owned "old cars", and had "early oils". And unreliable parts.
I am a former Maintenance Management Consultant. Notice the word "management", therefore not "technical".
But ...
Of course - I am an engineer - I heard and listened to technical experts in lubrication, bearings, etc. and was a speaker on, or attended several seminars where technical matters were presented.
I agree with Hans: oils have improved, motor manufacturing has improved, manufacturing tolerances are very tight, much more than when we were young. The only way to know if your oil or motor is "bad" is sending an oil sample to a lab. That's what they do with diesel engines of train locomotives. Because the cost-benefit is worth doing it. Not for a car. Not enough oil.
As long as my car is under warranty I will stick to the Ineos rule oil change "every 20000 km", after that it will depend on my behavior. And even with my former car I often went over the 25000 km without an afterthought!
Did you know that the "mean" life span of a bearing doesn't follow the "
bathtub curve"? For those who are interested in reading a fantastic book on these matters, read
RCMII, from John Moubray. RCM= Reliability Centered Maintenance.
Not very recent, but still very actual! Only the first chapters are eye openers! The further you go in the book, the more technical it gets.
Too much maintenance is only good for your mechanics shop, not for your car, and not for your wallet.