In Reply to: Oil Analysis results posted by Jack on September 21, 1999 at 08:06:52:
I have a few questions for you if you know or don't mind:
: I had my oil analized last week and just got the results back.
Which tests were conducted? Did the lab list the applicable ASTM designations.
: 1999 E46 328i 28,000 miles on the odometer
: 11,000 miles since last oil change with BMW synthetic 5W40
: (approx 50/50 highway/city)
: The reports states that the oil still falls within the spec'ed viscosity range (5W40)
Yeah, it falls within the range, but what was the value. How much, if any, had it changed since new?
: no trace of fuel, water, or antifreeze in oil.
Totally suspect. This sure sounds like they simply employed a method incapable of detecting these. No used oil can be totally free of these.
: and traces of metals (aluminum, iron, copper and about 4 other types of metal) were all virtually non-existant.
What's 'virtually non-existant' mean? Are we talking PPM or PPB. This sounds like one of those claims from a 50's nuclear test --- i.e. a 'little' exposure.
: traces of silica (dirt) are also very minimal. (using K&N air filter) (there was a side note that said air filter is
: working properly)
Again, what is minimal?
: The conclusion of the report was that the oil is suitable for continued use and engine is in excellent condition.
It may very well be, but the data they provided to you seems promotional rather than scientific.
: I think BMW engineers know what they're doing, and it'll be safe to go 15k to 18k before changing the oil.
Agree. The engineers know what they are doing, but they're not the driving force behind infrequent oil changes.
: When it hits 18k, I'll send the oil in to be analized again and will post the results.
That's useful. You can at least compare them to your current results. Were any tests done to determine the status of the 'conditioners' which are added to the oil. These are what one would expect to 'age' or deteriorate first anyway. I'm not knocking your efforts, just questionning the methods of test, the criteria, and whether the commentary they offer is in keeping with the data. (incomplete or otherwise.)
(An admitted oil-changer)