The enormous amount of misinformation about BMW's Oil change intervals

[markinva]

Originally Posted by Delta0311

What I don't understand is how the hell can BMW claim that the N52/N54 engine can be driven for 15k miles without an oil change. In all the previous BMWs that my friends and family owned the oil change interval was about 5k miles. So what kind of magic did BMW put into the new engines? In the end it all comes down to simple economics. BMW is paying for your oil change so they want to stretch out the intervals as much as possible.

pretty much everything you said, and the underlying assumptions to your questions are wrong. did you even read the first post?

[canucklion]

your attitude is pretty douche-y; if you want to start a constructive debate, I suggest you cool it with your 'guns a' blazing' mentality.

Originally Posted by markinva

And how are you an expert on what the oil condition sensor measures?

Aren't you speculating?

[canucklion]

ok, you're right, we're all wrong. Guys let's all agree with markinva aka Dr. Noel Itall.

Originally Posted by markinva

pretty much everything you said, and the underlying assumptions to your questions are wrong. did you even read the first post?

[markinva]

Originally Posted by canucklion

dude, that pdf proves exactly what carve said; the sensor measures the conductivity of the oil, take that value and 'sent to the engine management system. The engine management system uses the signal for internal calculations.."

I'm not disputing anything carve is saying about the sensor. I take issue with the notion that the system as a whole is flawed because when you put new oil in the mileage counter till the next oil change doesn't go up.

I'm pretty lost as to what you and carve are saying though...

[-=Hot|Ice=-]

Originally Posted by canucklion

your attitude is pretty douche-y; if you want to start a constructive debate, I suggest you cool it with your 'guns a' blazing' mentality.

Constructive debating and e90post don't go well together.

Now, if you were to say Hell raising flame wars, that would be another story.

[markinva]

I'm sorry, I can't have a constructive debate with people that the only reason BMW has longer oil changes is because they are paying for them.

[markinva]

Originally Posted by canucklion

your attitude is pretty douche-y; if you want to start a constructive debate, I suggest you cool it with your 'guns a' blazing' mentality.

sorry... I guess I'll stop being "douche-y"

Originally Posted by canucklion

ok, you're right, we're all wrong. Guys let's all agree with markinva aka Dr. Noel Itall.

are you saying that you agree with Delta when he insinuates that engines prior to the n52 and n54 had a 5k oil change interval recommended by bmw? Are you saying that you agree that "In the end it all comes down to simple economics. BMW is paying for your oil change so they want to stretch out the intervals as much as possible."

[canucklion]

What Carve is saying (please correct me if I'm wrong) is that the sensor is not a very comprehensive sensor. It uses a pretty primitive method to guesstimate (educated guess) when one should change their oil. It is a guesstimate because it measures the conductivity of the oil and uses that value to plug into a formula (or algorithm) that BMW derived to determine the oil change interval.

The attached was screencapped from that BMW document you attached

[markinva]

^Again, I don't take issue with that at all. But I speculate that the sensor isn't the only criteria that changes the "number of miles" until an oil change display. I think time and other factors like mileage are a factor.

I would think that if the sensor noted that oil was deteriorated (and it would have to be very deteriorated under carve's assumption) and you put brand new oil in, the mileage would STILL say you needed an oil change right now, because of those other factors, and because until you reset the thing It will say that.

[markinva]

why was this moved to the M3 forum?

[canucklion]

man, I'm just trying to enjoy myself on E90post while at work, all this thinking is hurting my brain!

dude, I agree w/ Carve on the sensor, and you seem to agree as well. Regarding the BMW moneygrab conspiracy theory, I'm indifferent to it, neither agree nor disagree, I just do my own in-between oil changes for the peace of mind. As someone said earlier, it's a pretty small price to pay for insurance.

[canucklion]

the mods forgot to take their meds

I'm kidding, I don't know why

Originally Posted by markinva

why was this moved to the M3 forum?

[CV335]

Originally Posted by Delta0311

Most of our cars are in the 40-$60k range. So I don't understand why some people just refuse to spend the $60 and do their own oil changes every 5k miles. It really takes about 10min to change the oil on a BMW. If you can afford the car than you sure as hell can afford to spend the $60 every once in a while.

+1. My Acura had scheduled intervals of 5k and I had to pay for those out of pocket. I don't care if there is not enough evidence suggesting 15k interval is enough or not. I'm not gonna bitch about paying $60-80 for an oil change, so my plan is to change the oil at least every 7.5k miles.

[bbbuzzy]

Most likely the explanation is a combination of many factors already discussed at length. Engine oil has been able to reduce friction for quite some time. Many examples exist that demonstrate an engine can run for some time without any oil remaining in the pan. Don't you remember the commercials for Castol as well as Nissan's VQ engine? Some of us have done this experiment accidentally.

If you're engine is run under normal conditions, the BMW recommendation is probably fine. Changing it early is insurance, nothing wrong with that if you are ok with consuming resources when not needed (don't worry, I change my oil more frequently as well). Economics definitely plays a role here as BMW's shift to longer intervals coinciding with their paying the bill is too coincidental to ignore. The likely reason for their shorter recommendation for their earlier cars was to help out the dealer network, you know, back scratching. Most people will still use a dealer to change the oil, convinced it's "necessary" to maintain their warranty. Go figure.

[742]

Originally Posted by 02themax

... I strongly believe that the turbos would fail prematurely if the oil wasn't in good condition. We'd be seeing alot of 335's blowing smoke out the tail pipe, even with low KM's, and even more with sludge problems but I guess only time will tell. ...

These problems can take a surprisingly long time to become evident. In the case of the Passat/A4 1.8T sludge issue it was about 7 years (give or take). It is also interesting that the problems were limited to the North American market.

[markinva]

Originally Posted by 742

These problems can take a surprisingly long time to become evident. In the case of the Passat/A4 1.8T sludge issue it was about 7 years (give or take). It is also interesting that the problems were limited to the North American market.

interesting. here's some internet forum speculation I've read on the audi forums. these engines only had 4.0 qt capacities, only used dino oil, and had no electric oil pump or cooling for the turbos after the engine gets shut off. All in stark contrast to the bmw setup (7 qts, oil cools turbo after shutdown (I think?), and speciific syn oil).

[02themax]

Originally Posted by markinva

interesting. here's some internet forum speculation I've read on the audi forums. these engines only had 4.0 qt capacities, only used dino oil, and had no electric oil pump or cooling for the turbos after the engine gets shut off. All in stark contrast to the bmw setup (7 qts, oil cools turbo after shutdown (I think?), and speciific syn oil).

That's kinda what I thought, synthetic vs dino, I think the water pump cools the turbo though. These intervals will be the norm for most vehicles soon.

[742]

Originally Posted by markinva

interesting. here's some internet forum speculation I've read on the audi forums. these engines only had 4.0 qt capacities, only used dino oil, and had no electric oil pump or cooling for the turbos after the engine gets shut off. All in stark contrast to the bmw setup (7 qts, oil cools turbo after shutdown (I think?), and speciific syn oil).

The VW 1.8T calls for VW 502 oil, which is a tough standard to meet and is always synthetic. Favorite oils are Mobil 1 0W-40 and Castrol Syntec 0W-30 – just like here in BMW land.

The turbos are water cooled, and there is flow with the engine shutdown.

That said, the sump is small and some owners/dealers did try to run dino. However it appears that even with the proper synthetic the engines will sludge (actually the problem is not "sludge" in the traditional sense) if the oil is left in too long or if the crankcase ventilation system is not working correctly.

The most interesting part of this mess is that it is a North American problem. Subtle differences in operating environment, fuel standards and who knows what else can have big impacts on maintenance requirements, occasionally to the surprise of the engineers. And this example shows how it can take time for these issues to surface.

[markinva]

Originally Posted by 742

The VW 1.8T calls for VW 502 oil, which is a tough standard to meet and is always synthetic. Favorite oils are Mobil 1 0W-40 and Castrol Syntec 0W-30 – just like here in BMW land.

The turbos are water cooled, and there is flow with the engine shutdown.

That said, the sump is small and some owners/dealers did try to run dino. However it appears that even with the proper synthetic the engines will sludge (actually the problem is not "sludge" in the traditional sense) if the oil is left in too long or if the crankcase ventilation system is not working correctly.

The most interesting part of this mess is that it is a North American problem. Subtle differences in operating environment, fuel standards and who knows what else can have big impacts on maintenance requirements, occasionally to the surprise of the engineers. And this example shows how it can take time for these issues to surface.

yeah, it's stuff like this that makes me want to change my oil in between the cbs intervals

[STE92VE]

Originally Posted by markinva

It's a pet peeve of mine when people spread rumors on the forums- well not necessarily the spreading of rumors, that's fine, I just hate it when rumors are presented as facts.

One of the first lessons you should have learned about the internet is that anyone can post anything and say it's fact. This was taught to my kids in grade school while taking information from the internet for school projects.

Unfortunately this misinformation can't be prevented and if it really peeves you, I suggest you stop using the internet as a source of information.

[carve]

Originally Posted by markinva

please tell me what this


Quote:
Originally Posted by carve
Go ahead and change your oil on your own and then tell me if the computer lengthens the time until it says you're due for your next change (hint: it doesn't!)


has to do with this:


Quote:
Originally Posted by carve
Reread my post. My point is, it's all based on the algorithm unless the sensor detects a LOT of conductive contamination in the oil. This would include metals and maybe water with dissolved ions, but it wouldn't include anything about silica (dust) or anything about the lubricity or viscosity of the oil. Many people, I think, are under the impression that the sensor is like an oil analysis lab in their engine.

__________________

They call it "condition based service". However, they just PREDICT what the condition SHOULD be for the most part- otherwise when you put in fresh oil it would recognize it as....fresh oil. This demonstrates that the sensor is just there as a sort of last resort safety factor in case the prediction completely screws up (e.g., your engine start shedding copious amounts of metal or you blow a head gasket or something). Nice to have since there is no dipstick to examine the oil manually, but nothing actually MEASURES the condition of the oil to any degree of accuracy beyond "probably OK" and "totally screwed".

Furthermore, their recommended change intervals are what they predict are needed to allow the engine to last for a particular amount of time. We have NO IDEA what their target is, nor their degree of certainty/safety factor used to hit that target. If someone knows I'd LOVE to hear it.

[carve]

Originally Posted by markinva

please tell me what this




has to do with this:

Originally Posted by markinva

interesting. here's some internet forum speculation I've read on the audi forums. these engines only had 4.0 qt capacities, only used dino oil, and had no electric oil pump or cooling for the turbos after the engine gets shut off. All in stark contrast to the bmw setup (7 qts, oil cools turbo after shutdown (I think?), and speciific syn oil).

(I thought I lost my mind when this was moved to M3)

OK...our oil pumps aren't electric- only the water pumps.

7qt of syn is WAY preferable to 4qt of fossil oil for resisting coking and for making is last longer. Still, hot running, 100hp/l turbo engines are more demanding on the oil, but the interval appears (yes- I'm speculating) unchanged from BMW's normally aspirated engines. That doesn't make sense. We also have no information about longevity goals BMW intended. I imagine the majority of people buying BMWs brand new don't keep them beyond the low 100k range, and already expect big depreciation, so that is a likely factor (yes, I'm speculating)

I'd be much less concerned running a (non-M) normally aspirated engine on the recommend change interval than a turbo or M engine.

In fact, when Subaru started importing turbocharged cars again (2001?), I think they had like a 5-7.5k mile interval, even on synthetic. By 2005 they changed that to 3,750 for all turbo engines, even if driven under mild conditions. Previously that was the interval for "extreme conditions" drivnig. Now they define merely HAVING a turbo "extreme conditions". The interval was implemented retroactively to ALL turbo subies. Think about it...they reduced their interval from 2x as often as BMW to 3-4X as often!