Re: <E39> Oil change interval

[Seeker <rfg@xxxxxxx>]

In response to Mr. Wallace's question, see below for best answer I've seen
on this question in the Digest over the last year or so.  Seeker.

In a message dated 03/21/2000 10:31:09 AM Eastern Standard Time, rfg@domain.elided
writes:

>   I am the owner of two BMWs, a 1992 525i and a 1996 328i.  I bought
>  the 525i in 1996 and the 328i in 1999.  Both have OBCs.
>
>   The 525 was purchased in San Francisco and driven directly to
>  Maryland, across country, at interstate speeds, so I was not too surprised
>  when I had put about 5000 miles on it and still had several green lights
>  still illuminated on the OBC.  After 8000 miles of driving, double any
>  interval I had previously allowed between oil/filter changes on any car I
>  had ever owned, I became concerned and called an independent mechanic (a
>  German) who owns his own shop who works only on BMWs and who had been
>  recommended to me by a former BMW owner.
>
>   His response was: "I can sell you a new engine or I can sell you an
>  oil/filter change."  So, I have been ignoring the OBC since and having the
>  oil/filter changed every 3500 to 4000 miles.
>
>   When I purchased my 328i last year, I mentioned the above to the
>  salesman.  He said a lot of work and sophisticated technology had gone into
>  that OBC and I should bring the car in for service according to when it was
>  indicated by the OBC.
>
>   Next I posted the question on the online BMW Digest.  I received
>  only a few answers and they all said ignore the OBC and have the oil
>  changed according to the odometer - every 3500 or 4000 miles.
>
>   Finally, I called the dealership where I purchased the 328i and
>  told them I'd like to bring it in for an oil change.  As this would be
>  their first servicing of the vehicle, they checked their records and found
>  that the oil had been changed in September 99, using Castrol 15/40  (4000
>  miles ago) and asked if the OBC indicated that an oil change was indicated.
>  I told them that there were still three more green lights to go before an
>  oil change would be due according to the OBC and related the above story to
>  them.
>
>   The service manager politely laughed and said he routinely sees
>  some cars come in at 12,000 and 15,000 miles for an oil change and that I
>  should come in when the OBC so indicates
>
>   What do you say?
>
>   Many thanks,
>   Seeker
>
>  P.s.  Really enjoy Tech Talk and find it the single most useful section in
>  the Roundel.

Hi Seeker.:

As you've discovered, you'll get as many answers to these questions as people
you ask. None are necessarily wrong or right -- in my humble option the
answer to the oil change interval question is, "it depends." Specifically, in
my opinion it depends on what kind of oil you're using and what kind of
service is demanded of the car.

Personally, I change petroleum oil around 3000 miles. Autostore quality level
synthetics or synthetic blends, maybe a little longer. When I use a high end
product like Redline, Amsoil, Lubromoly or Lubrication Engineers -- or the
BMW factory synthetic, I don't really have a problem leaving the oil in
service until the Service Interval Indicators tell me to change it. But
really, it also depends on severity of use. If you're doing a lot of track
work, autocrossing, extended high rpm cruising of the sort one rarely sees in
the US unless you live in the western states, or your driving consists almost
exclusively of short, low rpm jaunts, then I'd cut the interval 25 to 50%.

As you've noticed, older Bimmers want a oil change according to the Service
Interval Indicators around 9K miles. New ones, it's more like 15K. Anyone who
tells you the computer senses how you're driving and adjusts the interval
accordingly is either lying or simply doesn't know how the thing works.
Probably the later. All it does is keep track of fuel used. So, to the extend
that fuel usage is effected by hard driving, yes, it keeps track of your
driving style. But it doesn't count high rpm shifts, top speed, cold starts
or anything like that.

Also, it has to be recognized that the benefits of good drivetrain lubricant
maintenance do not accrue until the car matures. The difference between the
car that ran petroleum oil for 15K mile intervals and never had it's gearbox
or differential oil changed (as per BMW instructions) and the one that ran
high end synthetic lubricants and had it's driveline maintained in
contravention of BMW's instructions, is that the second car will be running
strong at 150K miles whereas the first car will probably have a worn out
drivetrain. BMWs, and most modern cars, will run 100K miles just fine with
zero maintenance.

So, if you're maintaining the car religiously only to sell it at 75K, then
you're a good guy for helping out subsequent owners. That's good, but to
realize the fruits of your diligence, you need to keep the car longer.

Hope this helps, and I'm glad you like Tech Talk!

Best regards,
Mike Mill

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