Due to oil leak, I have had to top up the engine oil twice about 1L each time. I have made a mistake to put 10W40 and 20W50 oil into the engine. No issues so far, but I was thinking that in the next service, should I do a engine flush? Is that advisable or just a normal service.

If engine flush is suggested, does anyone know what is the flush oil to use and how much on my '04 E60 525i sitting on 135K's.

Thanks.

 

I'd drain the oil after taking a highway drive -- 20-30+ miles and while the engine is still "warm". Most of the impurities will be in suspension in the oil and drain out nicely.

 

Thanks, but how much of the flush oil should I put when the car already has full oil? Sorry, but I am new of this, so the silly question.

 

NONE ... Overfilling your oil can cause harm!

I've never been sold on the "oil flush" gimmick and even when I've driven tons of miles (6K - 10K miles) between oil services by using quality synthetics and factory or OEM filters (MANN, etc) my engines have NEVER NEVER NEVER shown any symptoms of excessive wear, oil starvation, or blockage - but then again almost 80% of my driving was highway it had its share of stop and go city traffic - and I usually sold or traded them by the time they hit 200K++ miles.

 

I would be afraid of using any kind of flushing additive. If you really think that remnants of improper weight oil will be left once you drain it (or be harmful), change your oil now, and again in about a 500 miles. I think this might be overkill though. I would probably just drain the oil, change the filter, and fill with the proper weight oil.

 

Flushing is not a good idea, you will be running the engine on less than premium oil and may cause damage.

Either follow the advice of Stumpel or leave it alone.

 

God help you if you overfill your sump too far. The crank will strike the oil surface in your sump each time it makes a revolution and churn it, driving air bubbles into it. In minutes the oil will no longer lubricate and you can see massive journal bearing and rod bearing failure in short order.

Any flush that is strong enough to cut sludge cannot properly lubricate your engine. It is a marketing gimmick. Rapid changes of high detergent oil multiple times (very short drain intervals) can help, but won't entirely remove sludge. If an engine is very valuable (such as engines on some antique cars) the only proper way to remove sludge is complete disassembly and cleaning of individual engine parts. For most engines it isn't worth this type of rebuilding. For a normal engine drive it until it dies.

Unless you are seeing symptoms from sludge don't worry about it. Just keep changing your oil regularly.

 

Thank you for answers, so I understand that if the oil is max, do not touch it (I knew this).

Has anyone flushed there '04 E60(M54) 525i and know of a good flushing oil? How long should the flush oil be kept in the car before re-fill with normal oil?

 

Also, see some pics of engine cap and engine from the cap why I am thinking of flushing. Is it not sludge?

 

Those new pictures show evidence of condensate that could be the result of a number of things including lots of short trip driving at cold temperatures. If your usual driving doesn't permit your car to warm up fully you definitely should change your oil more regularly. For example, if following your iDrive mileage indicator I recommend you do a mid-cycle change. e.g. If your iDrive indicates 15K miles do a change at 7.5K miles - but do not reset the iDrive Condition based Service indicator at that time!

And ONLY use oils of the proper viscosity and grade as recommended by BMW and Original BMW or OEM Equivalent filters.

If at all possible, drive your car at "highway speeds" for at least 30 - 60 minutes at least once per week, Thoroughly clean the oil filler cap now and over time you should see some evidence of reduced sludge build up.

One last question - Are you seeing any evidence of coolant use? Sometimes [it's rare because internal engine pressures are usually higher than the cooling system pressures] , internal engine coolant leaks will evidence themselves similar to condensate in the oil.