Further test
TÜV Bayern Sachsen, 1993
The more often oil runs through the filter, the less dirt and water it contains. Chemically it hardly changes. The particles were counted in transformer oil.
Home/Tech & Practice
Field test
100,000 km without an oil change
The question: is oil still good after 100,000 km if you never change it and only filter it? A Renault R5 drove through towns, the countryside and on the motorway. Then its oil went on the test bench.
- Test car
Renault R5, diesel engine, 55 hp, very well maintained
- Distance
Odometer 80,000 to 180,000
- Oil
Mineral-based branded oil, SAE 15W/40
- Test device
Reichert friction wear balance
The distance
What happened along the way
- km 0Fresh oil, then the filter is fitted. The normal filter stays in.
- approx. km 1,000The engine runs more quietly.
- km 15,000New insert, 10 minutes at most. This repeats every 15,000 km.
- along the wayFuel consumption drops slightly.
- km 100,000The oil is tested, the engine parts are inspected.
The result is clear
Filtered oil lubricates better than fresh
- 1The testA test device presses a steel roller against a rotating ring that runs through the oil.
- 2The measurementIf the oil film holds, only a small spot is ground into the roller. A small spot means: the oil can take a lot.
In detail
The device is called the Reichert friction wear balance. The steel roller is pressed with 300 N against the ring, which runs at 1.65 m/s. The size of the worn spot gives the load-bearing capacity: how much pressure the oil film withstands.
1,00×
more loadThis is how much more pressure the filtered oil withstood than fresh branded oil.
So after 100,000 km the oil was not used up. It even lubricated better than when freshly filled. Against fully synthetic branded oil too, it came out 4 to 5 times ahead.
What else stood out
The observations
- 1A wafer-thin layer of carbon lay on the engine parts. The report rates this as positive: it can reduce wear.
- 2Changing the insert took 10 minutes at most, and afterwards the housing was tight again.
- 3The filter is not a throwaway part: when you sell the car, it simply moves to your next vehicle.
Who did the testing?
Test management: Wolfgang Staab (master motor mechanic), Horst Kiesler (master mechanic). Carried out by: Friedhelm Isselbächer (research associate). The standard filter stayed fitted, and missing engine oil was topped up with the same branded oil.
Further test
WEARCHECK Brannenburg, 1993
The lab certifies cleanliness class 11/8. The technical data explain what that means.
The report’s conclusion
Quieter, cheaper, cleaner
Less waste oil, a quieter engine and lower costs. The report assumes that the engine lives longer this way.
Report in the archive