[maxgohan]

Hey guys,

I had an +1L oil warning so I added oil to the car.
Few weeks later I got the warning again so I added more oil.

I asked the shop to figure out this oil consumption issue and they said when they drained the pan there was 9.5L of oil in it (over filled by 3L)

They changed the OZS (sensor) with an OEM brand new one but the new sensor still showed low oil after they added the 6.5L required. They reprogrammed all the ecus and it's still showing low oil

What could be causing this issue?

[AoS810]

I'm just curious, did the car have any weird symptoms when it was overfilled by that much? i.e. excess vibrations, rough idle, worse performance, etc. I've always read that overfilling can be worse than underfilling.

Did the shop scan your car and it pointed to the engine oil sensor? Would be helpful to know if you've got any other codes.

[maxgohan]

no codes for the sensor,
I did hear the lifters ticking and coincidentally got another oil low warning so I filled some more (FML) thinking the lifters were ticking cause of low oil....
this was just a day or two before I took it to the shop....

I didn't drive the car hard at all after I got the low oil warning....

[banglenot]

This has been documented a few times as water vapor condensing in the oil, pooling around the bottom of the sensor, and causing it to give a low oil reading.

It happened to me in the fall next to my lake house, when there were rapid temp changes and a humid environment. Suddenly one morning it was a quart low. But, nothing on the ground, so WTF? It's normal to have water condensation in oil as it cools, but usually kicking the temp up to 100C+ by driving boils it off.

It read low by a liter. I believe there is a SIB out there somewhere on odd sensor readings, but it's been years since I saw it.

Usual cure is to take the car out and run the temp up with a vigorous drive. That fixed it for me, and I'm still on the same sensor.

Only thing that's a puzzle here is that the replaced sensor is showing the problem, even when the new oil was installed (they did use 6.5 qts of new oil, didn't they?).

[maxgohan]

Yup they def used new oil.
They were able to drain some oil and confirmed the sensor was reading a lower amount but when they top it up the reading on their computer read only 74mm in the crankcase when it should read 90mm (according to them )

I doubt it would be the water vapor as they just did a fresh oil change in a temp controlled shop...

[Efthreeoh]

How did the engine get 9.5L of oil in it? Someone did something wrong.

When you say the e-dipstick read low after the new OZS was installed, what does that mean? Was it 1+qt low or some fraction a quart/liter

[maxgohan]

How did it get 9.5l, thanks to me cause I got the low oil warnings and put oil in. This was after valve cover gaskets so I thought maybe ship didn't top it up properly so I added oil until the warning went away.

The shop is saying the ecu is reading a max of 74mm in the crankcase when it should go to 90mm when full. The on board computer is reading the same low amount

[Efthreeoh]

Originally Posted by maxgohan

How did it get 9.5l, thanks to me cause I got the low oil warnings and put oil in. This was after valve cover gaskets so I thought maybe ship didn't top it up properly so I added oil until the warning went away.

The shop is saying the ecu is reading a max of 74mm in the crankcase when it should go to 90mm when full. The on board computer is reading the same low amount

How long did you wait until you checked the oil level after you added a liter of oil?

[maxgohan]

I was pulled over at the gas station when I filled it, after filling the oil I started up the engine and started checking the level.

usually it takes a few minutes for the sensor to come online and when it did it said the oil was back at max.....


now that I'm thinking about it, it seems that the new sensor is saying the same low oil when indeed it is full and prompting to add more oil....maybe my old sensor was working the same way and there's something else wrong? what could it be?

[Efthreeoh]

Originally Posted by maxgohan

I was pulled over at the gas station when I filled it, after filling the oil I started up the engine and started checking the level.

usually it takes a few minutes for the sensor to come online and when it did it said the oil was back at max.....


now that I'm thinking about it, it seems that the new sensor is saying the same low oil when indeed it is full and prompting to add more oil....maybe my old sensor was working the same way and there's something else wrong? what could it be?

Okay, you are not being clear on how 3 extra liters of oil got into the engine, so I'll assume you added too much oil by 3 liters. Here's why.

If you get a low oil level notification, the "+1qt" icon, and add oil while the engine is hot (like at a gas station), and immediately check the level, you'll get the same "+1qt" low oil level notification. The system only updates the level only every 20 minutes of continuous driving once the engine is warm and the car has been driven, so when you immediately check the level after adding oil, you get the previous (low) oil level reading. If you keep checking the oil level after just a few minutes and add in an additional liter, then you'll overfill the crankcase. The e-dipstick does not directly read the oil level, it calculates it over time. If you read the owner's manual, it tells you to only add 1 qt/liter of oil when the +1qt notification appears. The owners manual doesn't explain why only to add 1 quart/liter.

When the shop changed the sensor and added in 6.5L of oil, the reading came in low because 6.5L is sometimes not enough to fully top off the oil level to get a full reading (probably depends on the amount of residual oil remaining in the engine after draining). When BMW switched from quart bottles to liter bottles a few years ago. I would get a low oil level reading ( by 1/4 quart) after an oil change after adding in just 6.5 liters. When I did oil changes using BMW oil in quart bottles, I'd just pour in the entire 7 quarts (vs. the 6.9 spec), and never got a new reading other than full. It's just 4 ounces difference between 6.9 quarts and 7 quarts, but it makes a difference in getting a full reading (I let my engine fully drain obsessively). Now using liters, I pour in about 6.8L and always get a new reading at full.

So, IMO, there was nothing wrong with the oil sensor. It's more that you don't understand how the system works. That's not a flame, BMW just did a poor job at explaining it because BMW just expects owners to have their car serviced at a dealership. I figured out how the e-dipstick works only after a lot of research and several years of observation. I explain how the system works in this thread: (I was hoping the mods would make it a sticky...)

https://www.e90post.com/forums/showthread.php?t=1533444

[maxgohan]

That doesn't explain why I would get a subsequent low oil warnings 2 weeks after the initial warning.
The engine would have already had at least 8 liters in at that time and gave me the low oil warnings prompting me to add another liter....

I'll try driving the car around and see if the levels get fixed....

[Fritzer]

The timing of this thread is unreal!

My E90 had the +1L warning yesterday afternoon, almost to the minute of your post... I drove it home and checked the oil level once again and it said "ok". I filled it up with 1/2 quart of 5W-30 to be safe. I really wish they just put a f**king dipstick in the N51/2. I remember I got a code about half a year ago for a faulty oil condition sensor but it went away. I was thinking of changing the sensor next oil change in ~4,000 miles. But who knows what good that will do. Never had any signs of burning oil and fixed a couple gasket leaks recently.

[Fritzer]

Originally Posted by Efthreeoh

https://www.e90post.com/forums/showthread.php?t=1533444

Thank you for both posts, very informative! What do you think would cause my issue? Suddenly, after about 30 minutes of driving I got the +1qt notification. Drove around lightly for about 45 minutes afterwards to finish my business, then went home. Shortly before arriving home I checked the level once more and it was smack in the middle. I added about 1/2qt because I was wary of improper reading and didn't want to overfill. Took it driving after adding oil for about another 30 minutes later in the evening and all seemed fine, sensor reading smack in the middle once again...

Next oil change I think I'm going to let it drain twice as long. Since you seem very knowledgeable on this subject I might as well ask which oil do you use? I normally use BMW Genuine Synthetic 5W-30, however I have noticed there are some brands that offer "high-mileage"/"75,000+ miles" synthetic, which I have never used. Would it be worth it to try an oil with those additives or should I stick to BMW Genuine even at 125,xxx miles on my N51? Do you think it's even worth it to swap out the Oil Condition/Level sensor?

Thank you again for your posts, they're awesome.

[lowrydr310]

Originally Posted by Fritzer

I normally use BMW Genuine Synthetic 5W-30, however I have noticed there are some brands that offer "high-mileage"/"75,000+ miles" synthetic, which I have never used. Would it be worth it to try an oil with those additives or should I stick to BMW Genuine even at 125,xxx miles on my N51? Do you think it's even worth it to swap out the Oil Condition/Level sensor?

Stick with BMW approved oils (BMW LL01) and avoid any high mileage crap or other additives. BMW Genuine oil is approved and an excellent oil, go search for the guy who has over 300K miles on his E90 using that oil and changing it whenever the computer tells him to (I think he had intervals of 10-15K miles).

There are also many other excellent alternatives that are also LL01 approved. Mobil 1 5w-40 lost its approval recently but I still used it because it was on sale. I'm due for an oil change within 1000 miles and I'm going to get Castrol Edge 5w-40.

[TheMidnightNarwhal]

Originally Posted by lowrydr310

Stick with BMW approved oils (BMW LL01) and avoid any high mileage crap or other additives. BMW Genuine oil is approved and an excellent oil, go search for the guy who has over 300K miles on his E90 using that oil and changing it whenever the computer tells him to (I think he had intervals of 10-15K miles).

There are also many other excellent alternatives that are also LL01 approved. Mobil 1 5w-40 lost its approval recently but I still used it because it was on sale. I'm due for an oil change within 1000 miles and I'm going to get Castrol Edge 5w-40.

True. Although I will change mine every ~ 7.5k miles. (~ 12 000KM)

Same here. I would stick to what the manual says. I use Castrol Edge BMW LL01 0W-40. The only over the counter oil that you can easily get I think.

[Fritzer]

Originally Posted by TheMidnightNarwhal

True. Although I will change mine every ~ 7.5k miles. (~ 12 000KM)

Same here. I would stick to what the manual says. I use Castrol Edge BMW LL01 0W-40. The only over the counter oil that you can easily get I think.

The manual says 0W-40? For cold weather I'm assuming,up there in maple syrup land? Think I'll just go with 5W-30.

Originally Posted by lowrydr310

Stick with BMW approved oils (BMW LL01) and avoid any high mileage crap or other additives. BMW Genuine oil is approved and an excellent oil, go search for the guy who has over 300K miles on his E90 using that oil and changing it whenever the computer tells him to (I think he had intervals of 10-15K miles).

There are also many other excellent alternatives that are also LL01 approved. Mobil 1 5w-40 lost its approval recently but I still used it because it was on sale. I'm due for an oil change within 1000 miles and I'm going to get Castrol Edge 5w-40.

Gotcha! Going to go with the BMW Genuine Castrol. Where do you normally purchase from? 5W-40 over -30? I've always used -30 iirc. I only see BMW Genuine offer 5W-30 on FCP, the 5W-40 option is "LiquidMoly"(never heard of that brand). Has BMW Genuine ever done 5W-40, only see it listed on Motorrad for bikes?

[Efthreeoh]

Originally Posted by Fritzer

Thank you for both posts, very informative! What do you think would cause my issue? Suddenly, after about 30 minutes of driving I got the +1qt notification. Drove around lightly for about 45 minutes afterwards to finish my business, then went home. Shortly before arriving home I checked the level once more and it was smack in the middle. I added about 1/2qt because I was wary of improper reading and didn't want to overfill. Took it driving after adding oil for about another 30 minutes later in the evening and all seemed fine, sensor reading smack in the middle once again...

Next oil change I think I'm going to let it drain twice as long. Since you seem very knowledgeable on this subject I might as well ask which oil do you use? I normally use BMW Genuine Synthetic 5W-30, however I have noticed there are some brands that offer "high-mileage"/"75,000+ miles" synthetic, which I have never used. Would it be worth it to try an oil with those additives or should I stick to BMW Genuine even at 125,xxx miles on my N51? Do you think it's even worth it to swap out the Oil Condition/Level sensor?

Thank you again for your posts, they're awesome.

I've only used BMW 5W-30 oil in all my BMWs simply because I buy it a case at a time and the dealer charges less than $7 per liter, and it meets BMW spec (I buy one line and pick up at the dealer). I only use the OE MANN HU816 filter. My N52 just passed 357,000, so I'll testify that combo is good enough.

What I would do regarding the sensor is change the oil yourself, add 6.7 - 6.8L of BMW oil and then wait a day or two and take a reading of the oil level. Just to make sure the connector is not corroded, I'd unplug the sensor and spay the connector with CRC electrical connector cleaner, brush it with a toothbrush, let it dry, apply a small amount of dielectric grease, then reconnect the connector. When you do your own oil change and add in the correct amount of oil, then you have no doubt how much oil is in the engine compared to, and regardless of the reading. If you know how much oil is in the engine, and a few days later the low oil notification come up, then yeah, the sensor may be defective. The sensor is a pretty simple device and not prone to give false readings. It works on the dielectric capacity of the oil, it's possible oil that doesn't completely burn off the water in it from condensation may let the sensor operate correctly. That's just a theory that is passed around on E90 Post. I don't know how that can be verified.

You have to use some logic here. If you definitely know the starting quantity of the oil in the engine then the sensor should provide an accurate reading. If the oil level reports are different and show a drastic change of a short period of time, then either the engine is leaking oil pretty badly, or it is burning oil pretty drastically, which would be indicated by a wet tail pipe and smoke. People also think the oil pan gasket, OFHG, and VCG allow the engine to leak a lot of oil, which is simply not the case. Very little oil leaks form any of those places, even when the engine has all three leaking gaskets at once. With my cars, I just change the oil, add in the correct amount of new oil, then check the level after a few days. I've had symptoms like you reported, but I don't panic, I just let the system equalize of a few days and get its shit together. You live in San Diego, so the salty air, may be affecting the sensor connector cleanliness, which is why I suggest cleaning it.

Before your next oil change, wait till the oil level is reported at least 1/2 quart low, then drain the oil with the car level, and capture all the oil drained, even the few ounces in the oil filter housing. Then measure the quantity drained. I've done that several times and found the e-dipstick reading to be accurate.

Like I said in my thread about how the system works, you don't need to keep the engine topped off with oil. As long as the level is in the "OK" zone, the level is high enough to safely operate the engine.

[Fritzer]

Originally Posted by Efthreeoh

Like I said in my thread about how the system works, you don't need to keep the engine topped off with oil. As long as the level is in the "OK" zone, the level is high enough to safely operate the engine.

Awesome, great info. I really appreciate it, your posts are stellar my man. Thank you!

[TheMidnightNarwhal]

Originally Posted by Fritzer

The manual says 0W-40? For cold weather I'm assuming,up there in maple syrup land? Think I'll just go with 5W-30.

Well yes and no,

I read some threads and I thought the conclusion was 0w-40 was the best no matter where you were.