Vehicles built on or before JAN 2015 Should have their entire Timing chain + Guides + Sprockets + Tensioner + Oil pump chain, Guides and Sprocket replaced before the 120,000 KM or 80,000 Miles. This is because throughout 2015, the timing chain & oil pump drive system went through a variety of changes
Oil Pan Baffles:
RWD N2x, used in a performance/street application should look into having the sump updated to an Aluminium Pan + Baffle plate (URO sell the Aluminium Pan, and Navardi Tuned sells the baffle plates). The stock sump under high lateral left and right turns, including braking, causes the oil to move away from the pickup, causing irreversible engine damage from loss of oil pressure.
Turbo Feed Line:
Vehicles built before SEP 2015 should have their turbo oil feed line updated, BMW introduced a check valve to stop oil from draining from the turbo and causing bearing damage.
Diverter Valve upgrade, stock units are known to crack and leak under boost.
Charge Pipe upgrades, stock units are known to crack and leak under boost with age/heat-cylces.
Turbo inlet, stock units are known to crack
Oil Catch Can, helps eliminate carbon /sludge build up within the cylinder head/Intake valves and clean the intake/charge air system from oil and contaminates.
Known to be weak in the N20/N26, but can be reliable as long as the tune doesn't target high torque especially below 4000 RPM or exceed 550 NM of torque at the crank.
Cast pistons can fragile in nature, and it's important to ensure the tune does not run too lean as this causes the piston rings to fail or pistons to crack.
These pumps can fail at delivering correct amounts of fuel when tuned incorrectly or running exotic fuels such as ethanol that exceed the flow capacity of the pump, When the pump begins to fail or fail to deliver the flow demands the AFRs go lean causing piston/engine damage or component damage.
Cylinder Head Cracking:
Mostly unknown issue, but the issue stems from the threaded seat of the spark plug in the combustion chamber. The go-to fix is to machine down the spark plug seat in the cylinder head to reduce the amount of thin wallet material exposed to the combustion process. Once machined down, a spacer must be installed into the spark plug to ensure no spark plug threads are exposed in the chamber causing hot-spots/detonation. Refer to the following video on the issue/fix: https://youtu.be/nMXetr9coGk?t=835