BMW+Mobil 1=One Million Miles


You say your old 2002 has passed 200,000 miles and it’s still in pretty good shape? Here’s a ’90 325i that’s gone over ONE MILLION MILES.

The white 1990 325i coupe looks like many others you might see in New Jersey. If you sat in the driver’s seat and looked at the odometer you would be surprised to see a reading of about 5000 miles. Starting the 325i and driving it for awhile would tell you that the engine and drive train were all normal with the usual good handling and performance characteristics of a BMW. The only puzzling fact about this BMW is the mileage…can it be real? The answer is yes-but the odometer has gone completely around and the actual mileage is 1,005,000! The other amazing fact about this BMW is that the engine has never been overhauled, meets all environmental regulations and most of the engine mechanical parts are still within BMW normal specifications!

What’s the story behind this amazing BMW? It was one of three 1990 325is purchased by the Mobil Oil Research Labs in Paulsboro, New Jersey to be used for testing Mobil 1 synthetic engine oils subjected to the American Automobile Manufacturer’s Association (AAMA) 50,000 mile stop-and-go certification test. This particular BMW was broken in with about 1,200 miles of normal road driving before beginning the test using 5W-30 Mobil 1. The 50,000 mile test was completed easily and was never in doubt-as up to four test runs in series had been performed, without difficulity, on an American built vehicle.

Being the good research people they are, the Mobil technical staff were curious about how long you could run an engine without a failure when using Mobil 1 and Mobil’s super unleaded gasoline. Approval was given to run this BMW to one million miles (if possible) to really see what the limit was…the parameters for the long-term test were:

  • 5W-30 Mobil 1 and Mobil super unleaded would be used.
  • The BMW maintenance and service requirements would be followed completely.
  • The tests would be run on an outdoor instrumented roll stand, subjecting the test to changing weather conditions.
  • The hourly speed cycle on the roll stand would be 75% at 80-85 mph and 25% at 50-55 mph.
  • Full data collection would occur throughout the test including emissions and oil analysis.


The test was run over a four-year period on a night and day schedule that was equivalent to sixty-six-years of ordinary road driving by a typical American vehicle. During the course of the test, a few items failed-but not related to the lubricated parts of the engine.

The failure list was pretty short but included-two differentials, one drive shaft, one water pump and one automatic transmission. The injectors were changed at 680,000 miles because one injector showed slight signs of deposits.

Once the testing period was completed, the engine was removed and completely disassembled for inspection. The results were astonishing!

  • The engine was extremely clean and free of deposits.
  • There were no visible top-of-stroke cylinder ridges.
  • Cam lobes and valve guides showed little wear and were in excellent operating condition. (The cam shaft rotated over a billion times during the test.)
  • With 2 exceptions, all the engine parts were within BMW specifications. The exceptions were…
  • The No. 2 piston ring end gaps were .004″ over.
  • Two con rod bearings were .0008″ over.

Following the inspection, the engine was reassembled without replacing or cleaning any of the components except for new seals and gaskets.

The 325i has since been driven to Las Vegas for a Mobil dealer meeting and back to Paulsboro where it is driven occasionally. BMW has looked at the engine and issued a paper on the test. The car has now been shipped to Europe for display and touring purposes.

You can come up with some mind-bending numbers if you compare this unique 325i to your own BMW experience. In my case, I have a 1974 tii with 28,000 miles, driven over 22 years. This 325i has to be the ultimate opposite extreme!

Bob Murphy is a long-time BMW CCA member with a background in petroleum engineering. He wishes to thank Bill Maxwell of Mobil Research & Development for his help with this story.

Last update: 2007-01-02 11:58
Author: Bob Murphy

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