[SiEgs90]

So I bought my car in May of this year and the carfax stated that the dealer I had bought it from changed the oil when they serviced it. As of right now my car is saying I need to have it serviced in October in the iDrive.. I had also had my car serviced for a valve cover gasket in July and the print out from the dealer said the usual green boxes for fluid levels checked/topped off. So what I’m wondering is if the dealer I bought the car from changed the oil and never reset the service light or if they never changed the oil at all. My car is showing that the oil level is ok. All bars are green. So should I just let it go with no change and reset the scheduled service time or just change it out to be on the safe side? And does the scheduled service reset to a new time frame each oil change or does the interval stay the same as the owners manual suggested service even if you change it say 2 months before or after the change. Thank you.

[123Britt]

Change it now and establish a new OCI & baseline of 7.5 K miles using LL-01 oil
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[Efthreeoh]

So first off you didn't specify the term "dealer". Did you buy the car from a BMW dealer, or did you buy it from a used car dealer? In light of me not knowing that here's my input.

You should do some searching on E90 post so you can get a good understanding of how your car works, how the CBS Maintenance system works (the owners manual explains it pretty well), and what the general issues that come up with ownership of a BMW E90. Engine oil in particular has been discussed on E90 post more than the meaning of life, to the point that it is ridiculous. But there is SO MUCH data on E90 post it would be difficult for you to get the specific answer you are seeking, but I hope I can help.

It sounds like you do not DIY your own maintenance, so you are left to professional mechanics to service your car. No problem there, but there is one axiom to follow with a BMW, which is never take it anywhere to be serviced that is not a certified BMW repair shop. That doesn't necessarily always mean a BMW dealership, but rather an independent shop that specializes in BMWs, or at least German cars.

You asked two different questions. You said your car is indicating it is in need of service, but you didn't elaborate what service. The CBS (Condition-Based Service) system monitors several separate service items and inspection items, that it reports on to the driver when they are due. Most maintenance items are both reported on as time based and conditioned based (reported as a mileage interval when next due). The time or mileage report is an estimate based on algorithms built into the computer module that controls the CBS. So what I'm saying is read the owners manual and determine if the service due is engine oil or an different service item that is now due in October. Assuming it actually is the engine oil that is due and the oil was report as being changed in May, then unless you drove the car around 15,000 miles since May, it would be unusual for the oil monitor to report an engine oil service is required.

How the oil life monitor works, in short, is this: The system uses an algorithm to calculate the oil change interval for when the next engine oil service is due. The algorithm uses many variables to calculate the interval including the historical change intervals, time, mileage, engine fuel use, engine warm up cycles, engine start counts, and measured engine oil quality (contamination). The last variable, engine oil quality, is actually measured using a sensor in the engine oil pan. It's the same sensor that determines the engine oil level. The sensor measures the dielectric property of the oil and compares it to a standard measure of contamination stored in the CBS computer. Use of an oil quality sensor is unique to BMW (and probably Porsche and Mercedes) and allows for extended oil change intervals. The algorithm (including the oil quality measure) doesn't work well for low annual mileage driven cars, so BMW recommends a minimum oil change interval of 12 months in the USA (it's 24 months in Europe). You will read on E90 post that the CBS oil change interval (OCI) is far too long and is a minimum of 15,000 miles, which is not actually true; there is no set 15,000 minimum OCI, it's just that the average is around 15,000 miles (my car routinely went over 17,000 miles per OCI). The CBS OCI topic is incredibly debated on E90 Post and the general consensus is to NOT follow it and cut the 15,000 mile (mythical) OCI in half and change the oil routinely at 7,500 miles (see post above).

But the post above did give some good advice. The oil change at the dealer is questionable at this point (if indeed your car is calling for an oil change after a reported oil service in May 2017). This gets back to my original statement/question, which is did you buy the car from a BMW dealer or used car dealer? If not a BMW dealer, then I'd suspect if they did change the oil, they probably did not use the correct BMW LL-01 spec oil and a correct original equipment manufacturer (OEM - you'll see that term used a lot on E90 Post) oil filter, and did not reset the CBS. So 123Britt's advice is sound, get the oil changed with oil that meets BMW specification known as LL-01 and use an OE or OEM oil filter. The OEM for the filter is MANN and the oil filter part number HU-816. The correct oil viscosity rating is either 5W-30 or 5W-40. As 123Britt stated, changing the oil now will set a baseline of time and mileage that YOU know is correct and then you can change the oil in accordance with the BMW CBS system, or with a set interval that you choose (such as 7,500 miles). Depending on how many miles you dive a year, the CBS mileage interval will vary or you may fall under the 12-month low-mileage annual oil change interval. The CBS does not reset itself when the oil is changed, the mechanic must reset the system through the computer.

Sorry for the long post, but the Oil Jackals will come soon and confuse the hell out of you with stupid advice, so I wanted to get a good explanation to you first. So just to qualify... I'm a 30-year BWW owner with over 800,000 total miles of ownership (on 4 BMWs). I DIY most everything. My E90 has over 332,000 miles on it. I've followed the BMW CBS system for maintenance and have only ever used BMW oil and OE filters in my engine N52 - same as the one in your car). I'm not advocating following the CBS per se, just saying you can and it will not damage the engine, but in most cases the extended mileage OCI doesn't come up in under 12 months of driving for most people.

[SiEgs90]

Originally Posted by Efthreeoh

So first off you didn't specify the term "dealer". Did you buy the car from a BMW dealer, or did you buy it from a used car dealer? In light of me not knowing that here's my input.

You should do some searching on E90 post so you can get a good understanding of how your car works, how the CBS Maintenance system works (the owners manual explains it pretty well), and what the general issues that come up with ownership of a BMW E90. Engine oil in particular has been discussed on E90 post more than the meaning of life, to the point that it is ridiculous. But there is SO MUCH data on E90 post it would be difficult for you to get the specific answer you are seeking, but I hope I can help.

It sounds like you do not DIY your own maintenance, so you are left to professional mechanics to service your car. No problem there, but there is one axiom to follow with a BMW, which is never take it anywhere to be serviced that is not a certified BMW repair shop. That doesn't necessarily always mean a BMW dealership, but rather an independent shop that specializes in BMWs, or at least German cars.

You asked two different questions. You said your car is indicating it is in need of service, but you didn't elaborate what service. The CBS (Condition-Based Service) system monitors several separate service items and inspection items, that it reports on to the driver when they are due. Most maintenance items are both reported on as time based and conditioned based (reported as a mileage interval when next due). The time or mileage report is an estimate based on algorithms built into the computer module that controls the CBS. So what I'm saying is read the owners manual and determine if the service due is engine oil or an different service item that is now due in October. Assuming it actually is the engine oil that is due and the oil was report as being changed in May, then unless you drove the car around 15,000 miles since May, it would be unusual for the oil monitor to report an engine oil service is required.

How the oil life monitor works, in short, is this: The system uses an algorithm to calculate the oil change interval for when the next engine oil service is due. The algorithm uses many variables to calculate the interval including the historical change intervals, time, mileage, engine fuel use, engine warm up cycles, engine start counts, and measured engine oil quality (contamination). The last variable, engine oil quality, is actually measured using a sensor in the engine oil pan. It's the same sensor that determines the engine oil level. The sensor measures the dielectric property of the oil and compares it to a standard measure of contamination stored in the CBS computer. Use of an oil quality sensor is unique to BMW (and probably Porsche and Mercedes) and allows for extended oil change intervals. The algorithm (including the oil quality measure) doesn't work well for low annual mileage driven cars, so BMW recommends a minimum oil change interval of 12 months in the USA (it's 24 months in Europe). You will read on E90 post that the CBS oil change interval (OCI) is far too long and is a minimum of 15,000 miles, which is not actually true; there is no set 15,000 minimum OCI, it's just that the average is around 15,000 miles (my car routinely went over 17,000 miles per OCI). The CBS OCI topic is incredibly debated on E90 Post and the general consensus is to NOT follow it and cut the 15,000 mile (mythical) OCI in half and change the oil routinely at 7,500 miles (see post above).

But the post above did give some good advice. The oil change at the dealer is questionable at this point (if indeed your car is calling for an oil change after a reported oil service in May 2017). This gets back to my original statement/question, which is did you buy the car from a BMW dealer or used car dealer? If not a BMW dealer, then I'd suspect if they did change the oil, they probably did not use the correct BMW LL-01 spec oil and a correct original equipment manufacturer (OEM - you'll see that term used a lot on E90 Post) oil filter, and did not reset the CBS. So 123Britt's advice is sound, get the oil changed with oil that meets BMW specification known as LL-01 and use an OE or OEM oil filter. The OEM for the filter is MANN and the oil filter part number HU-816. The correct oil viscosity rating is either 5W-30 or 5W-40. As 123Britt stated, changing the oil now will set a baseline of time and mileage that YOU know is correct and then you can change the oil in accordance with the BMW CBS system, or with a set interval that you choose (such as 7,500 miles). Depending on how many miles you dive a year, the CBS mileage interval will vary or you may fall under the 12-month low-mileage annual oil change interval. The CBS does not reset itself when the oil is changed, the mechanic must reset the system through the computer.

Sorry for the long post, but the Oil Jackals will come soon and confuse the hell out of you with stupid advice, so I wanted to get a good explanation to you first. So just to qualify... I'm a 30-year BWW owner with over 800,000 total miles of ownership (on 4 BMWs). I DIY most everything. My E90 has over 332,000 miles on it. I've followed the BMW CBS system for maintenance and have only ever used BMW oil and OE filters in my engine N52 - same as the one in your car). I'm not advocating following the CBS per se, just saying you can and it will not damage the engine, but in most cases the extended mileage OCI doesn't come up in under 12 months of driving for most people.

In May I purchased the car from a non BMW dealer, but a reputable dealer of other brands. I’m assuming they changed the oil and didn’t reset the service schedule as they’re not familiar with the car. In July I had it serviced at a BMW dealer and had some things fixed under warranty. I will just go ahead and change the oil on my own and use a window sticker for as long as I own the car. I’m more comfortable with the above posters advice of running it til 7,500. From what I’ve seen on YouTube changing the oil on this car is easier than what I had to do with my old car. I’m not paying a dealer X amount of money for something I can do own my own and not know what has actually been done to my car. I’ll just drop the money on the OEM filter and the ll-01 oil and be done with it. Thank you for all your help and information.