[Harry815]

I'm curious what rule of thumb you guys follow.

Say if you haven't done an oil change since October 2022, but you've only driven 7000 miles since then. The BMW recommendation is every 10,000 miles for the car I drive (a 2018 540i).

Do you guys follow the time interval of at least once per year, or reaching the Mileage interval?

[AP]

That the big debate
Here in the U.K. and I think EU aswell we have a 2 year/19000 mile service intervals

I got a m550 last year and I’m going to get the oil changed annually . My annual mileage will be something like 8000 miles per year

I have a service pack which covers me for services up to 62000 miles or 5 years, which ever comes first but I will pay out of my pocket for an additional one at the 1 year mark and ask the service reminder to be not reset.

No doubt I’ll get some pushback on that with the dealer saying it’s not necessary but as this car is a keeper, I think it’s a sensible thing to do.
There’s lots of info out about this and the consensus I’ve come to )I’m not a mechanic) is that it’s worthwhile

Can’t see it affecting warranty ) how could it?!)

[adhrp]

I always cover 9K+ miles a year, so for me the 10K interval coincides with a year. If I were at 7K, I would be comfortable waiting 1.5 years until I got closer to 10K. This is a contentious topic with many different opinions.

I saw a video on YouTube recently where they didn't drive the car much and didn't change the oil for 2 years and when they got it tested, it passed with flying colors. No condensation or other issues that are typically thought as concerns with longer duration OCIs.

[eric_gm]

I have asked this in plenty of places myself. Since the pandemic, it takes me ~3-4 years to put 10k miles in any of my cars, so if I stick to 1 year intervals, virtually brand new oil goes to waste (it's still golden when it drain it). Not to mention 4 cars = 4 yearly oil changes = lots and lots of non-recyclable plastic, oil filters, etc.

The general consensus is unfortunately that nobody knows and oil companies won't tell you either for obvious reasons.

The best information I could find was in classic car forums where people rarely drive them. There, 3 or 4 year oil change intervals are common. But we're talking 50 year old cars, so it's not apples to apples.

People who insist on at least yearly changes say that oil sitting in the engine absorbs humidity, but it all evaporates as soon as you drive the car for more than 30 minutes, so it's a non issue. Others say that oil has an expiration date which is when the additives start to break down (which is true), but if you check the bottles, it's at least 5 years. True, the moment you break the seal you're exposing the oil to the elements but in a relatively sealed system like a car's engine it should still last for quite a while.

We get scared because of all those pictures and videos of black gunk, but those are cars that are driven for too long without oil changes, a running engine is a hot and dirty piece of machinery. But I have never seen that gunk in unused cars with relatively fresh oil.

I would say that, as long as you use your car for more than 30 min once a month to avoid internal corrosion, full synthetic oil can easily last 2 or 3 years if you don't reach 10k miles. I'm sticking to 2 years, give or take, and I check the dipsticks often (no such luck with G30s). Haven't had any issues.

Of course I wouldn't listen to a random guy on the internet (me) and if you're unsure, stick to yearly changes.

[Chappers 71]

I change the oil when the car asks for it to be changed, the bmw system monitors the condition of the oil as well as the level, the last couple of oil changes on the e92 35i were time not mileage & I think mileage was around 3500 miles, prior to that the oil changes ranged from 12,000 to 8,000 miles dependant upon how hard it had been driven

[AP]

How does it monitor the condition of the oil exactly?
Just curious
I thought the service interval was based upon fuel consumption, the more fuel used , the harder the car driven or more stop start driving or cold starts which would indicate a shorter interval being required ? Or have I got that completely wrong?
More than happy to be corrected

[Chappers 71]

Originally Posted by AP

How does it monitor the condition of the oil exactly?
Just curious
I thought the service interval was based upon fuel consumption, the more fuel used , the harder the car driven or more stop start driving or cold starts which would indicate a shorter interval being required ? Or have I got that completely wrong?
More than happy to be corrected

This is the best description of how the BMW e dipstick works, was written for e9x but the principal is still the same, is quite a lengthy read

How the E-Dipstick and Oil Sensor Work
With the age of the E9X chassis now a good 6 years past its last production date and most cars still on the road are with their second or third-tier owners (who probably are missing the original BMW documentation), I decided a write up of how the oil monitoring system works in the N52/54/55 engines was in order. A lot of owners have no idea how the oil sensor works, and misunderstand how the e-dipstick operates and what it tells them; the BMW owners manual never really gave a good explanation in the first place. A lot of owners do not understand the e-dipstick bar graph and think it represents the entire 7-quart quantity of oil in the engine. It only represents the top quart of oil.

Oil Sensor Purpose:
The N-series engines in the E9X all use VANOS, which is a camshaft timing system to vary the timing of valve operation dependent upon engine load (power) requirements. VANOS is operated by relatively constant oil pressure in conjunction with varying oil volume flow though computer controlled solenoid-operated oil control valves. To insure proper operation of VANOS, the engine computer needs to determine the level of the engine oil, which is why the engine has an oil level sensor. The primary purpose of the oil level sensor is for the VANOS system, rather than to just notify the driver of the engine oil level. The e-dipstick is an adjunct function of the oil level sensor even though it offers the driver convenience of reviewing engine oil level from the driver’s seat. The oil level sensor operation is not well understood by most owners, and appears to give faulty readings, which is why owners suspect its reliability.

Oil Sensor Design:
The sensor design is quite simple. It uses a dual stack of concentric-ring capacitors to determine the oil quality (contamination level) and oil level. Dual stacked means one capacitor is on top of the other capacitor. Capacitors are an electrical device normally used to store electrical energy for short periods to provide electric devices with short bursts of electrical energy when needed. Capacitors use a dielectric material to store the electrical energy. For the BMW sensor, engine oil is the dielectric material; the BMW oil sensor uses the electrical-design theory of the capacitor as a measurement device rather than an electrical energy storage device. The oil sensor, called “OZS” by BMW, uses the lower capacitor to measure the oil quality and the upper capacitor is used to determine the oil level. The sensor measures the dielectric value of the oil against a dielectric constant (value) to determine the contamination level of the oil. The upper capacitor uses the value (amount) of the capacitance in the upper capacitor based on the amount of oil present to determine the engine oil level. Concentric-ring means the design of the capacitor stores the oil in between conductors of the capacitor to determine the dielectric value of the oil (imagine a small pipe inside a larger pipe with oil in between the two pipes). There are small openings at the top and bottom of the OZS housing that allow engine oil to slowly pass through the capacitors. There is very little to mechanically or electrically to break in a capacitor, which makes the BMW oil sensor device highly-reliable. For the OZS to correctly measure the oil, the temperature of the oil must also be known, so there is an oil temperature sensor built into the bottom of the OZS.

E-Dipstick Operation:
Mechanical dipsticks are direct-read devices, meaning the level of the engine oil in the crankcase is directly determined by presence of oil on the dipstick. The e-dipstick is not a direct-read device; it takes data and data analysis to determine the oil level, which also means it takes time to determine the oil level; BMW calls this the "dynamic oil level" measurement. To get an accurate oil level reading the oil must be at operating temperature (one of the reasons the OZS has a temperature sensor built into it), and the engine must have been in operation for a minimal time period and gone through a series of operational parameters to ensure oil has moved throughout the lubrication system while the engine is running. The engine operating temperature must reach and be above a minimum of 140 deg. F. Engine speed must have reached greater than 1,000 RPM, and the engine must have reached acceleration levels transverse (side to side) and longitudinal (forward) of greater than 12 – 15 feet per-second squared. It takes about 5 minutes to reach these parameters in normal driving and the e-dipstick will not provide a measurement until such time, which is why if the engine is cold, a small clock symbol appears in the e-dipstick window and no reading is provided. Once the time and other parameters are met, the e-dipstick updates to a new level reading. The engine computer then continuously monitors the oil level and updates the e-dipstick display every 20 minutes, which means you can only get a new level reading after every 20 minutes of continuous driving.

Static oil level measurement. The OZS also has a function to measure the oil level when the engine is cold (like after an oil change) to confirm you refilled the engine. Static oil level measurement at engine OFF is only a reference measurement as the oil condition sensor (OZS) is flooded when the engine is turned off and can only detect the minimum oil level [the oil level is measured correctly only when the engine is running]. After switching on the ignition, the static oil level measurement provides the driver with the opportunity of checking whether there is sufficient engine oil for safely and reliably starting the engine. You follow the same procedure as checking the dynamic oil level, the action will return the "OK" notification in the gauge cluster.


The Confusion:
This is where the problem occurs with oil filling of the E90 N-series engines. Most owners don’t understand the e-dipstick doesn’t immediately update the oil level measurement (as a mechanical dipstick does). The e-dipstick reports only the top-level quart of oil, meaning it only shows how much of the 7th quart of oil is in the engine. The bar graph, which is analogous to the upper and lower marks on a mechanical dipstick, is just 1-quart long, so if the bar graph shows halfway between MIN and MAX the engine is missing just 1/2-quart of oil (i.e. not 3.5 quarts). If after an oil change and complete refill of the engine crankcase (7 quarts), if the engine is still above 140 deg. F (or soon does reach 140), but the engine has not gone through the full 5-minute time period of reaching the operational parameters, if the oil level is read, the e-dipstick will report the last known oil level. So if you changed the oil when the engine was, for example ¾-quart low, the e-dipstick will still read ¾-quart low even if you added the full 7-quarts of new oil. Conversely, if you top off the engine when it is not a full 1-quart low, say again at ¾-quart low, and then immediately read the oil level, it will still show ¾-quart low. This gets confusing to owners, because they don’t trust the oil sensor and don’t understand how it works, so they will add more oil and overfill the engine; I had a good friend, who is a very experienced DIY’er, do this exact scenario and blow the front crankseal of his son’s N52. This is also why, if you read the owner’s manual, it tells you to only add 1-quart of oil to the engine only after the CBS notification (“+1QT”) appears in the information display; if you add the quart and then immediately check the oil level, it will still show 1-quart low.

So as an owner of an E9X with the N52/54/55 engine, when changing the oil, or topping off, you must allow the e-dipstick at least 20 minutes to provide an update to the previous engine oil level. Also, you do not need to keep the engine oil level at MAX. Allow the engine to consume the 7th quart of oil and only add replacement oil at 1-quart increments to top off the oil level as notified by the CBS. Add the 1-quart of top-off oil within 125 miles of receiving the "+1QT" notification.

[AP]

Thankyou for that, appreciated.
Now I know

[Chappers 71]

Originally Posted by AP

Thankyou for that, appreciated.
Now I know

You’re welcome…every days a school day

[Neusser]

Originally Posted by eric_gm

I have asked this in plenty of places myself. Since the pandemic, it takes me ~3-4 years to put 10k miles in any of my cars, so if I stick to 1 year intervals, virtually brand new oil goes to waste (it's still golden when it drain it). Not to mention 4 cars = 4 yearly oil changes = lots and lots of non-recyclable plastic, oil filters, etc.

The general consensus is unfortunately that nobody knows and oil companies won't tell you either for obvious reasons.

The best information I could find was in classic car forums where people rarely drive them. There, 3 or 4 year oil change intervals are common. But we're talking 50 year old cars, so it's not apples to apples.

People who insist on at least yearly changes say that oil sitting in the engine absorbs humidity, but it all evaporates as soon as you drive the car for more than 30 minutes, so it's a non issue. Others say that oil has an expiration date which is when the additives start to break down (which is true), but if you check the bottles, it's at least 5 years. True, the moment you break the seal you're exposing the oil to the elements but in a relatively sealed system like a car's engine it should still last for quite a while.

We get scared because of all those pictures and videos of black gunk, but those are cars that are driven for too long without oil changes, a running engine is a hot and dirty piece of machinery. But I have never seen that gunk in unused cars with relatively fresh oil.

I would say that, as long as you use your car for more than 30 min once a month to avoid internal corrosion, full synthetic oil can easily last 2 or 3 years if you don't reach 10k miles. I'm sticking to 2 years, give or take, and I check the dipsticks often (no such luck with G30s). Haven't had any issues.

Of course I wouldn't listen to a random guy on the internet (me) and if you're unsure, stick to yearly changes.

"The general consensus is unfortunately that nobody knows and oil companies won't tell you either for obvious reasons."


But they do know, and they are so sure that they put it into your BMW manual.

[Qsilver7]

Originally Posted by Harry815

I'm curious what rule of thumb you guys follow.

Say if you haven't done an oil change since October 2022, but you've only driven 7000 miles since then. The BMW recommendation is every 10,000 miles for the car I drive (a 2018 540i).

Do you guys follow the time interval of at least once per year, or reaching the Mileage interval?

Isn't there a screen in iDrive that gives the date/mileage for the next oil service?

This image below is from older versions of iDrive...did they remove this info in the newer versions?

[Rocket455]

With these newer cars, I just wait for the car to tell me when it's time.

Originally Posted by eric_gm

The best information I could find was in classic car forums where people rarely drive them. There, 3 or 4 year oil change intervals are common. But we're talking 50 year old cars, so it's not apples to apples......True, the moment you break the seal you're exposing the oil to the elements but in a relatively sealed system like a car's engine it should still last for quite a while.

100%. I have 3 classics that I rarely drive and get the oil changed once every 3-4 years, usually coupled with some other maintenance or upgrade visit to the shop.

[eric_gm]

Originally Posted by Neusser

But they do know, and they are so sure that they put it into your BMW manual.

The same manuals that say "lifetime fluid"? Tell that to those who had E39s and E46s and trusted it.

I'm not ready to wear my tinfoil hat and call conspiracy, but I think car manufacturers simply don't want to risk it and parrot what oil companies state (10k or 1 year). The reality is definitely much more complex and there is some information around regarding this, especially after a lot of people started working from home during the pandemic. I'll keep my 2 year intervals which is probably 5k miles or less and I'm seriously considering extending it to 2.5 years.

If we all had the habit of sending oil for analysis before changing it, we would probably find that it was still good for twice that time (assuming no mileage was met). But oil analysis is not free and it's a bit of a chore having it done.

[adhrp]

Originally Posted by eric_gm

If we all had the habit of sending oil for analysis before changing it, we would probably find that it was still good for twice that time (assuming no mileage was met). But oil analysis is not free and it's a bit of a chore having it done.

There was so much hemming and hawing and plain misinformation surrounding the 15K OCI BMW had and how it was ruining engines. My 328i did 15K OCIs the first 50K miles when the maintenance was covered by BMW and after that I started doing 10K intervals. I got the oil tested by Blackstone and it was in excellent condition, so much so that they recommended going higher next time, which essentially would have been a 15K OCI.

[Neusser]

Originally Posted by eric_gm

The same manuals that say "lifetime fluid"? Tell that to those who had E39s and E46s and trusted it.

I'm not ready to wear my tinfoil hat and call conspiracy, but I think car manufacturers simply don't want to risk it and parrot what oil companies state (10k or 1 year). The reality is definitely much more complex and there is some information around regarding this, especially after a lot of people started working from home during the pandemic. I'll keep my 2 year intervals which is probably 5k miles or less and I'm seriously considering extending it to 2.5 years.

If we all had the habit of sending oil for analysis before changing it, we would probably find that it was still good for twice that time (assuming no mileage was met). But oil analysis is not free and it's a bit of a chore having it done.

I've done the extended services with three cars now here in Germany and have never had a problem.

Oil is pretty critical and the extended service programs have been common for quite some time.

If you are chipped/tuned this will change things of course.

[eric_gm]

Originally Posted by adhrp

There was so much hemming and hawing and plain misinformation surrounding the 15K OCI BMW had and how it was ruining engines. My 328i did 15K OCIs the first 50K miles when the maintenance was covered by BMW and after that I started doing 10K intervals. I got the oil tested by Blackstone and it was in excellent condition, so much so that they recommended going higher next time, which essentially would have been a 15K OCI.

Totally right. If I trusted my E39s Oil Service Indicator I would go past 25k kms (15k+ miles) between changes. Since it's based on fuel consumption that means if I don't use the car that much, getting to the "oil service" warning would equal 6 or 7 years at the current rate. I would never leave oil in there for that long, so those BMW indicators are flawed, or at least they were in older models. Not sure if the G30 is smarter in that regard.

That being said, if I used the car intensively and were adding 15k miles to my E39 in a year or two, I'm pretty sure the engine would be fine and nothing would grenade.

https://www.bimmerforums.com/forum/s...6#post29923106

[Qsilver7]

Originally Posted by eric_gm

Not sure if the G30 is smarter in that regard.

Since 2014…BMW has programmed the cars in the US market to 10k/12 months….so if you don’t drive over 10k miles per year…in 12 months you will get an OIL SERVICE warning.

[ezaircon4jc]

Originally Posted by Qsilver7

Since 2014…BMW has programmed the cars in the US market to 10k/12 months….so if you don’t drive over 10k miles per year…in 12 months you will get an OIL SERVICE warning....

And it won't go away until the service is preformed &/or reset. It's quite annoying to have that thing stare at you. My SA advised I could wait until my car was eligible for the $225 special, which was just a month as I was well under (over 2K) the mileage.

[Joe-BMW33]

For me, it's 6 months or 5,000 whichever comes first. Most of the time it's six months. Overkill for sure, but no one ever said it hurts the engine to change the oil too much.

But in general, time supersedes mileage.

[Neusser]

Originally Posted by Qsilver7

Since 2014…BMW has programmed the cars in the US market to 10k/12 months….so if you don’t drive over 10k miles per year…in 12 months you will get an OIL SERVICE warning.

Still two years over here in Euroland.

I can't imagine doing it earlier if stock.

Mileage is more important than time, as if you don't drive much, the oil won't be doing much.

[Chappers 71]

My old N54 35i had engine & gearbox remap & some bolt on go faster bits & I only changed the oil (Castrol Edge) when the car asked me to do so, I did over 70,000 miles in that car & it was mostly driven hard with a fair few trips to the drag strip. It had done over 125,000 miles when I sold it & it’s still going strong now with the current owner.

[G30M]

what does BMW manual say about "harsh" driving conditions?

note harsh = heat in oil degradation speak

IMO the M550i is 100% "harsh". this thing is so darn hot.

i do 12 months or 6000 miles (10,000km)