Oil level drops from 3/4 full to Min level in 15 min highway drive.

[Rajmun340]

First some context:

Right off the bat from the factory my car seemed to consume oil between oil changes (yearly oil changes done every ~6k miles). The dealer who ordered the car for me has been topping the oil whenever the car displays the infamous 'add 1 qt oil' message. Now 3 1/2 years later i recognize a definite pattern that oil seems to drop on highway trips. Quite predictively I would start a highway journey and after 2 hours of highway the oil level would have dropped by 1/4 of the difference between min and max. What is strange is that if i drive only on local roads for an entire season without stretches on the highway the oil level doesn't budge.

The issue :

So over a month ago this happened I was 3 hours away from home on a highway trip : 'oil level low: add 1 qt of oil' . I went to the nearest bmw dealer and they added 1 qt. I resumed my journey and oil went to Max and stayed there for the next 3 hours highway drive back home (take note of this for what follows). I arrived back home, level still read at Max. Then just 2 days later on a local drive i get the warning 'Oil level too high ! Visit you bmw service center. ". Went to my dealer and they flushed the oil and changed the oil sensor. When I got the car back it read 3/4 level between min and max. Forward 1 month later and i am off to another half day trip on the highway. Level had been at 3/4 and I took note of it on my way to the gas station before starting the trip. After 30 min of highway the car alerts me : "oil level low, add 1 qt". Dropping from the 3/4 marker to the min level in just 30 minutes of highway drive had never happened before. I was dumbfounded and stopped the car at the next exit to check for an oil leak, found none. I drove a bit more and arrived at my destination. There i parked the car for ~25 minutes. Then as I powered it back up and drove in the city the car measured oil level once more, back to 3/4 !! I drove the car a bit more locally it stays at 3/4. Then evening comes and i am on my way back home on the highway again, same thing, not even 30 minutes into the trip i get a minimum oil level reading and 'oil level low : Add 1 qt" warning. Then i swear at bmw engineers. Needless to say i am bringing it to the dealer.

Maybe anyone experienced something similar ? I know the sensor is known to be flaky but this is far beyond what i've seen before they replaced the sensor.

[BanjoPaterson]

I'd get another sensor. Sounds like they traded a bad sensor for another bad one. Not outside the realm of probability.

[srmast1]

This is exactly why we need a dipstick for the s65! It's so finicky with its oil requirements AND we cannot manually check the oil level. Dammit, just makes no sense. I am not an engineer, but I wonder if having a dipstick would drop the engine compression?

I do experience oil levels dropping faster if I drive long distances, especially with continuous driving. I'll periodically drive 3.5 hrs north to San Francisco or 3.5 hrs south to LA and I want to say that the oil level will drop once a trip. I have not experienced the crazy fluctuations that you had Joe, but the oil level in my car does drop a bit on trips.

[shimmy23]

i believe the carly app reads the true oil level. do you have that app to give it a try?

[Rajmun340]

So I drove the car locally today thinking the reading may return to 3/4 as it has before, but it stayed at Min. I reviewed the dashboard photos I took yesterday and it's actually worse than what i stated :
dropped from 3/4 to min in only 15 minutes of highway drive.

Could the mechanic have not installed the new sensor correctly or do these things just snap in place without room for error ? If the original sensor was bad then the replacement is unusable.

I won't buy a car without a dipstick again that is for sure.

The oil level sensor is read electronically. I don't know if the data gets averaged before being displayed in idrive and I don't have Carly. But i don't think any functional data processing can explain the sudden drop and return and drop again between 3/4 and Min.

[Solo_M_Tech]

Originally Posted by JoeM3SSII

So I drove the car locally today thinking the reading may return to 3/4 as it has before, but it stayed at Min. I reviewed the dashboard photos I took yesterday and it's actually worse than what i stated :
dropped from 3/4 to min in only 15 minutes of highway drive.

Could the mechanic have not installed the new sensor correctly or do these things just snap in place without room for error ? If the original sensor was bad then the replacement is unusable.

I won't buy a car without a dipstick again that is for sure.

The oil level sensor is read electronically. I don't know if the data gets averaged before being displayed in idrive and I don't have Carly. But i don't think any functional data processing can explain the sudden drop and return and drop again between 3/4 and Min.

You can't really install the oil level sensor incorrectly. So they either installed a factory defect part, or you have another issue. Potentially a partially blocked oil drain back passage. The pump moves all of the oil to the top of the valvetrain, but cannot return back to the pan fast enough. Just a thought.

[Rajmun340]

Originally Posted by Adenau

You can't really install the oil level sensor incorrectly. So they either installed a factory defect part, or you have another issue. Potentially a partially blocked oil drain back passage. The pump moves all of the oil to the top of the valvetrain, but cannot return back to the pan fast enough. Just a thought.

Thanks for the info, it got me thinking.. if there was a partially blocked oil drain back passage shouldn't the level have gone back up overnight ? It still reads min today. I cannot think of a scenario that works. If the true level was at Min with a false reading of 3/4 Max after they replaced the sensor, how could it have stayed at false 3/4 for 550 miles (all non highway drive) then dropped suddenly to Min after 20 min on the highway then recovered back to false 3/4 at the destination and dropped back down again suddenly on the drive back in 15 min and stayed at min overnight ?

[Solo_M_Tech]

Originally Posted by JoeM3SSII

Thanks for the info, it got me thinking.. if there was a partially blocked oil drain back passage shouldn't the level have gone back up overnight ? It still reads min today. I cannot think of a scenario that works. If the true level was at Min with a false reading of 3/4 Max after they replaced the sensor, how could it have stayed at false 3/4 for 550 miles (all non highway drive) then dropped suddenly to Min after 20 min on the highway then recovered back to false 3/4 at the destination and dropped back down again suddenly on the drive back in 15 min and stayed at min overnight ?

It's tough to say for sure. I see your point about the level remaining the same overnight. Only thing that comes to mind is the sensor is sticking. The sensor isn't anything special. I would return to the dealer and have them check it out again. If it's truly a litre low, they should be able to drain the oil into a clean container and measure the actual amount of oil removed. If it's a litre less than spec, then your car is trapping or consuming oil somewhere.

Makes me wonder about the anti drain back valves used in the vanos system. ......

[rcracin]

I think you'd have oil pressure issues if a drain passage blocked. Debris can throw off the sensor reading. I'd drain the oil and pull the sensor to inspect. I'd also do my best to measure how much oil comes out although it isn't very accurate.

[Rajmun340]

Originally Posted by Adenau

It's tough to say for sure. I see your point about the level remaining the same overnight. Only thing that comes to mind is the sensor is sticking. The sensor isn't anything special. I would return to the dealer and have them check it out again. If it's truly a litre low, they should be able to drain the oil into a clean container and measure the actual amount of oil removed. If it's a litre less than spec, then your car is trapping or consuming oil somewhere.

Makes me wonder about the anti drain back valves used in the vanos system. ......

I'll be at the dealer monday and will ask them to start an oil consumption log by draining the oil, measuring how much comes out and how much they put back in. I feel they should have started a log after replacing the sensor but didn't. I re-read the work order and it says "Calibration error. Drained oil and installed to correct level. still showing level too high. drained and installed new oil level sensor."

I can see the Vanos non-return valves on the hydraulic schematic of oil supply in the 'aftersale training.pdf'. It also shows non-return valves for the chain lubrification in cylinder banks. If a non-return valve starts to leak backward would that create a surplus of oil in the pan except after steady RPM highway drive ?

[Rajmun340]

Originally Posted by rcracin

I think you'd have oil pressure issues if a drain passage blocked. Debris can throw off the sensor reading. I'd drain the oil and pull the sensor to inspect. I'd also do my best to measure how much oil comes out although it isn't very accurate.

I brought the car to the dealer. They had it for a day and said the car is not loosing pressure and there were no faults. Oil consumption is 650 miles / 1 quart supposedly within bmw specs (which again is absurdly high at 380 miles per qt in TIS for M cars. That would mean if someone went on a week long road trip, they would have to bring a qt bottle of oil for each day, seven bottles ! that's bmw, how absurd !!)
I'm trying to get them to start a log of how much oil volume was drained and how much oil volume they put back in. I'm getting loose reactions from the SA. I'm not going to pick my car unless they give me these two numbers, as i need them to start a log.

[kimiraikkonen]

Originally Posted by JoeM3SSII

I brought the car to the dealer. They had it for a day and said the car is not loosing pressure and there were no faults. Oil consumption is 650 miles / 1 quart supposedly within bmw specs (which again is absurdly high at 380 miles per qt in TIS for M cars. That would mean if someone went on a week long road trip, they would have to bring a qt bottle of oil for each day, seven bottles ! that's bmw, how absurd !!)
I'm trying to get them to start a log of how much oil volume was drained and how much oil volume they put back in. I'm getting loose reactions from the SA. I'm not going to pick my car unless they give me these two numbers, as i need them to start a log.

What was your oil consumption like before this specific incident?

[Rajmun340]

Originally Posted by kimiraikkonen

What was your oil consumption like before this specific incident?

the average has been around 1,400 miles/qt but early on when it was factory new it consumed even more the worst case being at only 380 miles on the odometer (no typo!) oil reached the min level and 1 quart had to be added. And again when reaching the 1,200 miles mark just before 1st oil change it was nearly 1 qt low again. After that it varied between 1,200 miles/qt up to 2,800 miles/qt but now this last consumption log is 650 miles/qt.

I see a pattern that the high oil consumption numbers come with highway driving and the low oil consumption when the car is only driven locally.

[redpriest]

I guess BMW got tired of this in the F8X and it just tells you "OK" for oil level, it doesn't give you a level at all.

Weird behavior. They'll never be able to get all the original oil out as some of it stays in the cooler. Are they draining from both front and back sumps?

[Rajmun340]

Originally Posted by redpriest

I guess BMW got tired of this in the F8X and it just tells you "OK" for oil level, it doesn't give you a level at all.

Weird behavior. They'll never be able to get all the original oil out as some of it stays in the cooler. Are they draining from both front and back sumps?

yes, i believe they did, i think the technician said he let it drain for an hour.

[redpriest]

Originally Posted by JoeM3SSII

yes, i believe they did, i think the technician said he let it drain for an hour.

There's also a surprising amount in the oil filter housing. I use a turkey baster to get all of it out, it's about another .2 L at least.

[Kamen]

I don't understand how oil consumption can vary so much from car to car. I get that there are acceptable tolerances and that each engine is a little different, but it's hard to explain why some cars go through more than 10 times the amount of oil than others.

[Rajmun340]

Originally Posted by Kamen

I don't understand how oil consumption can vary so much from car to car. I get that there are acceptable tolerances and that each engine is a little different, but it's hard to explain why some cars go through more than 10 times the amount of oil than others.

Exactly, it's not normal and it is not acceptable. I have started reading on the topic and there are class action lawsuits against Audi, Subaru and Honda for excessive oil consumption, none against BMW yet but they are a top offender on the list. In the case of Audi they have extended powertrain warranty up to 10 years 150,000 miles to settle the lawsuit. A recall of every engine would cost them far more. The big picture starting to appear to me is that those manufacturers are committing fraud on the consumer and evading responsibility by bumping up their consumption spec numbers to cover their asses. This is exactly was bmw is doing. There is a growing discontent in the public about it and the law has given right to the consumer already and bmw is bunkering up and trying to shift responsibility away to the typical secondary factors. But a car fresh out of the BMW factory floor like mine that required 1 qt at 380 miles on the odometer is no driving style, climate, gas quality or other second order effect.

[Fanta]

I had that problem before, replace the oil sensor.
Dealer told me that the most accurate way to test it is, drain all the oil and measure the oil. No lie.

[dreamspeed]

I have a very similar situation. Oil will drop a lot very quickly during freeway driving. But if I stop the car on level ground and reset the oil reading it will display "correctly" again.

I have logged my actual oil consumption over many miles and burn around 1qt every 1800 miles or so.

If I calculate that I do need to add oil I just add half qt at a time

[GVIFlyer]

FWIW, there is a campaign to replace a leaky oil cap.

[Rajmun340]

Originally Posted by Fanta

I had that problem before, replace the oil sensor.
Dealer told me that the most accurate way to test it is, drain all the oil and measure the oil. No lie.

The oil sensor was already replaced. First post, 2nd paragraph.