I went to my colleague, who owns 2 workshops, and gathers a lot of data about cars that are repaired by him and his crew. I made a small graph based on this data.
Entry points: 195 cars, 2 – 26 years old that arrived with major engine failures between 2013 – 2024 (I could collect more data up to year 2005, but I wanted to focus on more modern cars that used more modern oils).
Data is gathered precisely by him, since he has a policy that he gives discounts for his services, but only if the oil is changed in his workshop before every 10 000 km* / 12 months*, whichever comes first (and he also gives warranty for rebuilding engines by him / warranty for labor for putting new engine for another 100k km (62k mi) / 3 years, but only if oil later is changed before every 8000 km** / 8 months**).
Major engine failures in the cars below 200k km (125k mi) driven, with reported oil change intervals:
– over 15k km (9k mi) – 72% (16 cars)
– 10k – 15k km (6k – 9k mi) – 14% (3 cars)
– below 10k km (6k mi) – 14% (3 cars)
Failures in cars that drove 200k – 400k km (125k – 250k mi) with reported oci:
– over 15k km (9k mi) – 62% (94 cars)
– 10k – 15k km (6k – 9k mi) – 27% (41 cars)
– below 10k km (6k – 9k mi) – 11% (16 cars)
Failures in cars with over 400k km (250k mi) driven with reported oci:
– over 15k km (9k mi) – 14% (3 cars)
– 10k – 15k km (6k – 9k mi) – 59% (13 cars)
– below 10k km (6k mi) – 27% (6 cars)
*in the case of full synthetic; in the case of synthetic blend – 7500 km / 9 months
**in the case of full synthetic; in the case of synthetic blend – 6000 km / 6 months
Even after reading your explanation, I don’t understand what I’m looking at.
So if your car reached 400 000km don’t change the oil, got it.
Is there a way to check if there is causation, not just correlation? Maybe owners of more expensive and better made cars are changing oil more often, and with better oil? Or people are caring more about their new car, but when they own it for many years they don’t care as much and change oil less often?
In my previous car I followed factory recommendation – 2 years or 30.000 km. Lasted 11 years and 120.000 km without problems, oil changed 4 times during that period, last change when it was 8 y.o., so 3 years on the same oil. No issues with engine whatsoever, if one plans to use car for 10 years or less, and makes polish average of 10-15k a year, I see no point in changing oil every 10.000 km.
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I went to my colleague, who owns 2 workshops, and gathers a lot of data about cars that are repaired by him and his crew. I made a small graph based on this data.
Entry points: 195 cars, 2 – 26 years old that arrived with major engine failures between 2013 – 2024 (I could collect more data up to year 2005, but I wanted to focus on more modern cars that used more modern oils).
Data is gathered precisely by him, since he has a policy that he gives discounts for his services, but only if the oil is changed in his workshop before every 10 000 km* / 12 months*, whichever comes first (and he also gives warranty for rebuilding engines by him / warranty for labor for putting new engine for another 100k km (62k mi) / 3 years, but only if oil later is changed before every 8000 km** / 8 months**).
Major engine failures in the cars below 200k km (125k mi) driven, with reported oil change intervals:
– over 15k km (9k mi) – 72% (16 cars)
– 10k – 15k km (6k – 9k mi) – 14% (3 cars)
– below 10k km (6k mi) – 14% (3 cars)
Failures in cars that drove 200k – 400k km (125k – 250k mi) with reported oci:
– over 15k km (9k mi) – 62% (94 cars)
– 10k – 15k km (6k – 9k mi) – 27% (41 cars)
– below 10k km (6k – 9k mi) – 11% (16 cars)
Failures in cars with over 400k km (250k mi) driven with reported oci:
– over 15k km (9k mi) – 14% (3 cars)
– 10k – 15k km (6k – 9k mi) – 59% (13 cars)
– below 10k km (6k mi) – 27% (6 cars)
*in the case of full synthetic; in the case of synthetic blend – 7500 km / 9 months
**in the case of full synthetic; in the case of synthetic blend – 6000 km / 6 months
Even after reading your explanation, I don’t understand what I’m looking at.
So if your car reached 400 000km don’t change the oil, got it.
Is there a way to check if there is causation, not just correlation? Maybe owners of more expensive and better made cars are changing oil more often, and with better oil? Or people are caring more about their new car, but when they own it for many years they don’t care as much and change oil less often?
In my previous car I followed factory recommendation – 2 years or 30.000 km. Lasted 11 years and 120.000 km without problems, oil changed 4 times during that period, last change when it was 8 y.o., so 3 years on the same oil. No issues with engine whatsoever, if one plans to use car for 10 years or less, and makes polish average of 10-15k a year, I see no point in changing oil every 10.000 km.
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