whoa dude.


20k? Thats nuts.


So vanos isnt so sensitive to viscosity...but crap in the oil, sludging up the screens in the vanos actuators WILL impact their motion. This causes the valve advance to be 'sloppy'. The DME is commanding one range, and ithe motor actually doesnt achieve that range fully or quickly. It doenst trip vanos codes, but it means the AFR will be off during those periods when the vanos is lagging or a bit off. Since the AFR is a long term adaptation, you get a persistent error (ie rich, lean) which is usually subcritical BUT affects cats, performance, throttle response.



Remind me, does your motor have two banks of vanos or one? My M5 has two, which is where I have all my vanos exposure. (My x5 is a D)

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.

Rebuilding a vanos at intervals was an m54, m52, and other older style vanos systems I believe. New vanos is solenoids coupled with valvetronic (again, I believe). I have never heard of rebuilding the vanos on any of the more modern BMW engines.

20k is a lot of miles. Annually I can understand, but 20k is longer than BMW's old 15k intervals and they (their customers) ran into all kinds of problems doing that. Sludge, wear, etc.

Frankly Im too annoyed to wade in. OCIs at 20k based on graphs?! SMH



You think you can look under the hood to figure out of you have separate vanos on bank 1 and bank 2?!? Google it.


https://us.autologic.com/news/bmw-vanos-system




good luck.

The calendar-year changes are mostly a thing of the past with modern oils. The OCI should be dependent on the specific oil you use and the type of drive cycles you operate on. Even then, the modern oils are much better at handling moisture and acids that can form when the oils doesn't get up to temperature for extended periods. When they reach their end of life, this ability can be reduced.

If your oil "sucks" then it might not support long OCIs well. If you accrue 11k miles over 20 years driving a mile to and from work every day, that's probably not conducive to longer OCIs either.

Really, the best way to determine your OCI by having the used oil analyzed to see when the TBN drops below an effective value, when wear metals increase above a desired threshold, the flashpoint is lowered, it thins out too much etc., etc.

Or don't. I'm not surprised you haven't had problems related to oil. Modern synthetics are fantastic and oil-related failures are ultimately rare no matter what oil is used. Also, 20k miles is not crazy-long. It's more than I'm comfortable with.

Oil is a contentious subject. It doesn't have to be. The oil I use in my diesel X5 is made by Mobil and although I do prefer Mobil 1 products, ultimately it's an oil that suits my diesel engine better than most with specifications that matter to the modern DI turbo-diesel: lowest SAPS, high HT/HS, stable 30W viscosity throughout life (based on my OCI analyses) and the lowest Phosphorus and Zinc. All specs that matter to a modern diesel with emission reduction systems.

What I'm trying to say is that with used oil analysis (UOA), review of the oil specifications, consideration of your vehicle and how you use it, it should be no problem determining what oil to use and how often to change it and be sure your maximizing your dollar and vehicle life.

That being said, you really don't know if dirty oil, or more aptly, your oil's inability to handle the increase in wear metals and the like, has contributed or is contributing to VANOS maladies that might be causing you issues. It is a fact that VANOS can be finicky and difficult. Fortunately, there is tons more VANOS information out there now than the dark days of the last and early this century. At 11k miles, oil is probably not your problem.

Ard is talking about the double VANOS on the E39 M5. It uses two VANOS banks that each control the intake and exhaust cams over each head. As an L6, you probably have a single bank controlling the intake and exhaust cams but some engines had VANOS that only controlled a single cam.

The VANOS test may reveal interesting data as would a UOA.

Good to know about the VANOS being less likely to need a rebuild these days.

The wife averages around 8K miles a year now, so if I'm changing annually, it's normally around 8K on this vehicle. It's at 11K now just b/c life has put me behind the curve a bit. I'm working now to restore my universe to its proper order.

Interesting idea. Any idea where I would go for a UOA, and what it costs? The State agency I used to work for did that with their vehicles & equipment, but I don't know a place where one can just walk in and have it done on demand. Maybe I'll Google.

I thought I might be able to tell by the shape of the cover, but no, you are right. So, I did Google pics of the N52 last night. Looks like dual VANOS, with one on the intake and one on the exhaust.

I don't see that affecting only Bank 2, but then I know strange things happen sometimes with trouble codes.

Failed solenoids (if lucky, dirty solenoids) is a very common problem with the N52. A faulty valvetronic is much less likely. I recently bought an e61 with the n52 that had been seriously neglected and had 180000 miles on it. Lots of sludge under the valve cover, stumbled/missed on idle slightly but not enough to throw a code. I cleaned the solenoids, changed the plugs, all coils (one was mis-matched), valve cover gasket, and flushed the engine twice with SeaFoam. Been a great daily ever since with no unusual idle, great throttle tip in, etc. Point being I don't think your issue with the code/stumbling is an oil problem. You could clean the solenoids for S's and G's, it's an easy 20 minute affair involving only a couple of 10mm bolts and a couple harnesses.

But I think you're going to have to find someone with a BMW specific code reader. I think it would speed things up tremendously. I find when working on BMW's... P codes are not very helpful in many cases. And stored codes (not active codes the ECU retains) can be equally valuable to a diagnosis.

OK, I've been siderailed with holiday stuff, company, etc., over the past couple of weeks from pursuing anything related to the main purpose of this thread. Hope to get back on it soon and at least get these upstream O2 sensors changed out. I'll post when I do.

Meanwhile, can't resist posting these 2 pics regarding the 20K oil change interval products. Do I realize that companies often over-tout the performance of their products for sales/advertising purposes? Yes, of course I do. However, it's a free country and I chose several years back to try out these products and the 20K intervals, b/c I was spending so much at the time on fuel and oil changes. Sure, I know it was a gamble but so far as I can tell, it's worked out (although as I discussed in previous posts I've never gone past 11K in the X).

You know, people once thought tomatoes were poisonous. Then, some guy decided to risk everything and try one on a BLT and he didn't die. I can understand anyone not wanting to try a tomato. Just lucky for me that guy did, though, else I wouldn't have any ketchup for my cheeseburgers and fries.:D
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