My 2005 bmw 325i is now reaching 248.450 miles, while that may look like an akward number in miles it translates to 400.000km's which is above average high in europe and most normal people think a car will not make it this high.
This n52 engine puts out 220hp out of a 2.5l inline 6. This means it puts out 88hp per liter. For example a 2005 lamborghini murcialago produces 580hp out of a 6.2l v12 making it 93.5hp per liter. A 2005 dodge viper makes 60 hp per liter and a corvette c6 makes 71.
Considering this i would say that because of this it can be considered as a pretty ''high'' performance motor meaning that a lot of horsepower is squezed out of a pretty small normaly aspirated high revving engine.
Hauling a 1600kg stationwagon around, towing boats and trailers and driving 110mph/180kmh for hours and hours on cruisecontrol on the highway makes me think this engine has seen a pretty ''hard'' life. It also sees 7000rpm regulary.
It has seen 5w30 ll04 oil all its life and has always had its oci at 18k miles/ 30k kms.0
Motor is fully original as is timing chain etc..
I think the trick to achieve this comes from multiple factors:
- Well built/designed engine with appropriate tolerances and decent timing chain. It cosumes a quart per 2200 miles by design, they all do this.
If there is an inherent flaw in engine design you can use the best oil you want but the problems will come sooner or later.
- Using high quality oils, it has seen Castrol, Total, Shell and Fuchs throughout its life.
- Maintaining the OCI's according to how the vehicles is used. It mostly sees 100+ mph highway runs 50 miles a day. This gets the oil up to temp nicely and thus ''cleanses'' it from moist / fuel etc.. I think most people underestimate that they only make short trips and a lot of people also do this very ''slowly'' never letting their engine work out/get it up to temp causing sludge and dilluted oil etc..
A lot of people advised me to go to a thicker oil but i am not a believer in that thicker oil offers more protection. My idea is that as long as a good film is maintained this is sufficient. A lot of modern race and rally cars are running superthin oils.
I think in average an engine is designed to make it up to 200k miles with 20k ocis and only short distance trips. Then it should be fully worn, full of sludge and discarded like the rest of the vehicle. This is how economics work, only us bitogers think we will take our cars into the grave.
I think in the past 20 years its also clearly visable cars are designed to not last as long anymore, but this is compensated because the manufacturing and tooling processes are so good these days.
20 years ago it was much harder to make cars as good as they are now. So this basicly evens it out.