BimmerFan52

You say you drive 35 miles per day, but don't say how long it takes you (city or highway). Oil life is most accurately measured in hours of operation but since most vehicles don't have hour meters you need to estimate if you want to base your change intervals on hours.

The magic of modern oil is additives and once they are gone the oil quickly looses its properties.

City driving and short trips are very hard on oil as contaminants from unburned fuel and condensed water build up quickly. Gasoline in the oil makes it acidic and is very hard on gaskets and seals.

If you like the car and want to keep (and not spend a fortune on repairs) I suggest you shorten your oil change frequency (7.5K or even better 5K miles).

The reason you have sludge is because the dirt and contaminants suspended in the oil by the detergent settled onto the engine walls once the detergent was used up, and if you start running a high detergent oil with the objective of pulling deposited sludge off engine walls, the detergent will suspended it in the oil only as long as the detergent lasts. You can quickly clog your oil filter and once the detergent is used up the suspended sludge will settle back to the engine walls. You must drain the oil while detergent still exists.

Using a quart every 15K miles is insignificant, especially given the number of miles on the engine and the previous oil change frequency. I would stay with a 5W-30 (or at most a 0W-40 if you drive the car hard). A higher grade only will doing nothing but exacerbate you problems.

If you are not experiencing engine problems now just shorten your oil drain frequency and you should be OK.

jimadams7

Thanks u have a good point I think maybe change the oil and filter myself is it hard to do

BimmerFan52

Piece of cake - Use search feature on this forum with your model car (didn't see it listed but I may have missed it).
Let us know if you can't find anything and one of us can steer you to a DIY or I can send you something out of a repair manual.

luigi524td

Sorry but I have respectfully offer my opinion - using the oils "recommended" by BMW makes 5K mile oil changes overkill. Low-mileage drivers will find that once per year changes will prevent contaminant build up. I've owned and driven BMWs to very high mileage (150K miles - 300K miles) over the past 20+ years without a lubrication related failure. Changing a high quality synthetic every 5K miles won't hurt [except your wallet] but those oil change recommendations harken back to the days of no-low detergent oils and toilet paper filters.

BimmerFan52

I, in turn, must respectfully disagree with you.

The OP did not answer as to his driving habits. Does he drive 15,000 miles at 60mph on the highway, or at 10mph in traffic commuting across a major city? If 60mph the oil would have 250 hours on it, which is reasonable. If 10mph the oil would have 1500 hours on it. At 1500 hours there would be no additives left, especially given the severe conditions of stop and go.
Oil life is correctly measured in hours. The oil industry conducts stress tests in actual engines in order to qualify oils for certain ratings. Many of the stress test lasts 300 hours, about as far as you want to push oil safely. If driving habits include short trips the oil never reaches operating temperature in order to burn off water vapor, which will condense into the oil.

His question related to attempting to dissolve existing sludge. So instead of the oil being placed into a clean engine and having the contaminant level build slowly over time, the high detergent oil immediately begins to dissolve the sludge and suspend it. Immediately the oil is exposed to soaring levels of contaminants and severe loss of detergent. If left too long (and it won't take long) the detergent is used up and the sludge again settles to the engine parts. In his case in order to clean up his engine he might consider 1500 or 2000 mile oil changes to quickly get rid of the contaminants.

Modern engines, especially turbocharged and piston squirter engines are very hard on oil. Once the additive package in any oil (syn or dino) is used up the oil?s characteristics change dramatically for the bad. Sludge is a function of severe oxidization coupled with loss of detergent. Once detergent, which normally keeps contaminants suspended, is gone the contaminants settle onto engine parts and are cooked into a gel-like goo. Not only are fine oil passages blocked, but the sludge sits between the engine parts and oil, preventing the oil from doing one of its most important jobs ? drawing heat out of the engine. Search "BMW engine sludge" on the internet to see how many engines have been ruined by BMW's CBM program. If you lease a BMW then I agree, who cares. Not your problem. The engine will hold together for at least 50K miles. But if you want to keep it long term, not wise to follow 15K mile drain intervals.

Given that all group IV oils provide superior base stock stability and excellent low temperature kinematic flow, the real magic of modern oil is in the additive packages, which allow the oil to act as though it has different viscosities at different temperatures, keep contaminants suspended and compensate for contaminant acidity. Oil testing labs such as Blackstone are available to test oil for contaminants and TBN (total base number which measures the reserve alkalinity of the oil ? basically what percentage of additives are left).

I have used Mobil 1 for 30+ years (began just after M1 hit the market). In each vehicle I have owned I have used 6K mile drain intervals, and I have never had even one engine failure or gasket failure in all the cars I have purchase new and driven to 100K miles: BMWs, Porsches, MBs, Infinitis, Lexuses, Toyotas, Nissans and Hondas.

Could I safely extend my oil drain intervals? Most likely. My daughter commutes to college averaging 70mph. Yet I change the oil every 6K miles. The engine probably only runs 100 to 125 hours between oil changes, but I don?t have the time to worry about which of my three cars is doing what. They all get the same treatment ? 6K miles with M1 full synthetic.

Now, if I owned a fleet of 400 taxi cabs, you can bet each one would have an hour meter and samples would be sent to labs regularly in order to find out how far oil drain intervals could be safely extended. But for three family cars? Not worth the trouble.

How much more do 6K drain intervals cost than 15K drain intervals over 90K miles? Assume you change your own oil, use 8 quarts and buy the oil and filter at $6 and $10 respectively (total $58).
Changing every 15K miles you will change your oil 6 times for a total of - $348
Changing every 6K miles you will change your oil 15 times for a total of - $870
A little over $500 more over 90,000 miles. If you drive 1K miles per month (12K per year) that is 90 months of driving or a cost of $5.80 more per month. Many people spend that per day at Starbuck's.
How much will you pay for a valve cover gasket replacement? Or worse a lower timing case gasket or alternator bracket gasket. Acidic oil attacks gaskets making them brittle and prone to failure. And a number of BMW models (my 545i included) have poor engine gasket designs to begin with, and fail even with TLC. They don?t need an extra push over the edge from acidic oil. Is it worth $500 to me that any one of my engines can be opened and look brand new inside. ABSOLUTELY.

Each of us has to decide what represents a good value. Some people would be horrified at spending an extra $500 over 90,000 miles for more frequent oil changes, yet think nothing of spending $4K to $5K on accessories for their car. To each his own.

Given my personal experience, IMHO frequent oil changes using quality synthetic oil is very, very cheap insurance. Change your oil every 250 hours, 6K miles or 6 months, whichever comes first, and your car?s engine will love you for it and repay you in kind.

NoQuarter

BimmerFan52. As always, much respect for your posts.

I have been working on building a a custom computer module that does some cool things I like to do with my car. One of the features I am working on is based on the education I get from your oil posts. My controller will log run time hours to provide some guidance on oil change interval which I can compare to BMWs CBS. I am also monitoring oil temp so I imagine I could be clever with the code and log frequency of the oil actually being at operating temp.

Cheers!

BimmerFan52

Thanks.

Your idea sounds way cool! And marrying your data with some timely oil analysis from a lab should really tell a detailed story of how oil ages in your car.
If the module can plug right into the car I would be willing to try one on mine and get some oil sampled to give you feedback. And I'll bet others would as well.

You may have a very marketable idea as the module could be set for the type of car and type of oil used before installation. It would be neat to get a text message from the module to your phone telling you that based on average speed, rpms, average duration of operation for each start and oil temperature it estimates that your additives are getting low and it is time to change your oil.

Attached is an article I found interesting regarding GM's efforts along these same lines.

Regards

StasGS4

I truly think that the 15K oil change recommended by BMW was their way to save money when offering complementary maintenance. I change my oil twice a year (spring and fall). These intervals are about 5K miles apart.

BimmerFan52

Twice a year is perfect if you are averaging about 10K miles per year.

You are right track when you say BMW extended oil changes in order to save money based upon free maintenance.

Some time back the auto manufacturers began competing with each other for bragging right to lowest total cost of ownership (TCO) for a car within a certain car market segment. It was based upon sales price, fuel cost, estimated maintenance costs and estimated depreciation. Some of the luxury car brands began offering free maintenance while others extended the miles between recommended maintenance items in order to be able to claim a lower calculated TCO. You will see in most car magazine reviews estimated maintenance costs. In extended reviews (where car magazine keeps the car and drives it for a year) they actually document maintenance and repair costs.

By increasing drain intervals for all fluids BMW has saved a tremendous amount of money. They also herd those customers into the dealership for the "free" oil change who if they had to pay for a dealer oil change would probably use a lower cost option or one that is closer to work or home. Of course every time you go to the dealer and the car is on the rack they have the opportunity to "find something" that needs to be addressed as well as potentially sell you another car. The honest dealers stick to the required items. The less than honest ones constantly find trouble.

BMW rarely has to do warranty repairs because of the extended drain intervals so they are ignoring the sludge factor. BMW also directs the dealerships to deny warranty repairs based upon customer complaints until the warranty ends, at which time the problem suddenly becomes one that must be fixed (out of your pocket).

For those who purchase a vehicle or even lease it with the intention of keeping it long term, I would suggest that they let the dealer continue to do oil changes based upon the CBM computer. Then, using the same or a similar BMW approved oil, slip an extra oil change in between each one BMW does for free. Even reducing the oil change frequency to 7500 miles is a huge improvement and will greatly lessen the chance of building sludge or damaging the engine.

jimadams7

Thanks bimmerfan . How do u know so much about this stuff .
I did my oil change today the oil didn't look as bad as I thought it would considering I had done so mouch km between oil changes but I twice a year sounds like a good idea and its not that much when u do it yourself