Yes, I have been running full synthetic oil with long change intervals for close to 20 years now. Never had an oil related problem before. I used to go 15K. Then probably about 10 years ago, after studying their published viscosity vs. mileage charts, I started with the Castrol Titanium at 20K intervals. I was commuting almost 200 miles r/t per day at the time, so it was a big help. Still no observed oil related problems, while approaching 300K with some of those rides before selling them off for other reasons. I used to replace filter only, halfway through the interval, but later just started buying extended life filters. Maybe these products don't live up to their long-life hype, I don't know. But, I got started on them and it seemed to work out.

Anyway, in this case with this vehicle, the wife doesn't log that many miles. It's been a little over a year and a half but only a little over 11K. I would have normally changed it about 6 months ago but haven't. The current problem started before then anyway. Would have normally attended to that much sooner as well but the whole having my head put back together with 5 titanium (there's that word again!) plates and having my mouth rebuilt just seemed to slow me down for a while.

Not sure if by two banks you mean like for cylinders 1-3 and 4-6, or one for intake and one for exhaust? Thinking it would have to be the separate intake/exhaust thing since it's an inline 6 motor and there is only one intake camshaft and one exhaust camshaft, right? From reading a few sites I think that is what's known as dual VANOS, which for some reason is what I was thinking I have. But, come to think again, I'm not sure. I'll have to look next time I'm under the hood to see if I can tell.

I read on one site that the VANOS needs to be rebuilt after about 50K and that by about 70K a rebuild is a must. You really think so? Seems kind of excessive.

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2009 X5 3.0
2001 X5 4.4 - Sold