Is the N63 reliable?

The original N63 (built 2008 to 2014, in the X6 and X5 xDrive50i, 550i, 650i and 750i) had genuine, well-documented problems: high oil consumption, turbo failures, valve stem seal leaks and injector issues.

They were severe enough that BMW ran a customer care package, cut the oil interval from 15,000 to 10,000 miles and made owners a loyalty offer toward a new BMW.

Its first update, the N63TU1 (2013 to 2019 in the 550i, 650i, 750i, X5 and X6), drew a class action over oil consumption, which led to a settlement and a BMW service campaign in 2022. That history is real, and the internet remembers it loudly.

The N63TU2 (in the 2018 to 2019 M550i) and TU3 (the 2020 to 2023 M550i and every M850i) are revised engines. For the M850i, BMW USA lists:

• a stronger block alloy;
• reinforced pistons and rings;
• larger twin-scroll turbos;
• injection pressure raised from 2,900 to 5,076 psi;
• and reworked heat shielding and cooling.

Neither has drawn a class action or a customer care package like the original and the TU1, but they have bulletins of their own:

• BMW covers injectors corroded by coolant on 2019 to 2021 cars for 15 years or 150,000 miles (BMW bulletin SI B01 17 24);
• and M550i cars built before June 2018 could need a cooling repair for coolant leaks (BMW bulletin SIB 17 06 17).

Each car's page also gives its own reliability score, which counts its known issues and age, with the reasoning written out.

• Oil consumption. Better than the early engines, but still there. Ask any seller how often they top it up between changes.
• Heat. The hot-vee layout (turbos inside the V) stresses gaskets, hoses, and the cooling system. Leaks show up with age, and a cooling repair on a high-mileage car is routine upkeep for this engine.
• Injectors. On 2019 to 2021 cars, coolant residue can corrode them; BMW covers the repair for 15 years or 150,000 miles, so check coverage by VIN.
• Valve stem seals. A common repair on the original N63 and the TU1; no bulletin covers the later engines. On a high-mileage car, watch for blue smoke at start-up, ask how much oil it uses, and have a specialist check the spark plugs for oil.
• Intervals. We advise oil changes every 5,000 to 7,500 miles, sooner than BMW's yearly or 10,000-mile schedule.

Budget like a V8 owner. These cars cost clearly more to run than a B58 six (reliability 92/100). That is the trade: V8 character and near-M pace, for the running costs that come with it.

Our estimates: an M550i runs $600 to $950 a year in routine service, and its 19-inch staggered tires cost $1,200 to $1,900 a set. The M850i's 20-inch tires ($1,600 to $2,200) and bigger brakes ($1,800 to $3,200 a job) cost more.

• M550i, the near-M5 sleeper with 523 hp from 2020: the 2018 to 2020 car and the 2021 to 2023 facelift
• M850i, the V8 grand tourer: the 2019 to 2022 coupe and Gran Coupe and convertible; from 2023, the facelifted coupe and Gran Coupe and convertible

Each page lists the known issues with inspection advice, plus the Guide Score and its three parts, with the reliability reasoning written out.

The N63's reputation was earned by the original engine and its TU1 update, not the TU2 and TU3 in these cars.

Buy one with documented short-interval oil history and its injector coverage checked, budget for V8 upkeep, and pay a specialist to inspect it before you buy. A well-kept one is a fast, comfortable car; a neglected one gets expensive quickly.