Morning Boreas
Welcome to the Forum
As an old engineer I have never been a fan of extended oils changes which just about all Manufacturers have advocated since the early 1990's around the same time the use of plastics for chain guides also became common along with simplex chains instead of duplex. With extended oil services (sometimes 30k) all these things have lead to chain stretch and guide wear BMW engineers didn't help themselves by moving timing chains to the rear of the engine ???
Common issues I have heard of are (1) Chain Stretch my feeling is this is avoidable if frequent oil changes are carried with good quality oil. While stretch is going to happen it can be delayed and top chains can be split and changed in situ. (2) Chain tensioner failure is often confused as chain stretch so fitting a new tensioner (around £30) with an annual Oil and Filter change I believe is good practice. (3) Chain Guides these are plastic and will always wear over time and use but regular oil changes with good quality Oil and Filters will help extend their life My brother inlaw runs 5 series and is on his 5th as he has a business based in Holland he travels extensively in Europe and all his cars have exceeded 200k one 300+ they have also all been ECU tuned from new, they have all been 6 cylinder models and Oil is changed every 5k religiously His current car is a 540d xDrive with well over 400hp he also uses the cars to their full and has had no chain issues.
All the 1 series engines 3 cylinder 4 cylinder and 6 cylinder now have the chain at the rear, so if there is any noise, misfires or misfire codes on a diagnostic scan walk away ( unless you are able to DIY). If mileage is low and service history is good with evidence of at least annual oil and filter changes the risk is low, my first job would be an oil and filter change with the tensioner
Hope this lengthy post helps not hinders
Dave
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Greydog ·