Mazda MX-5 NC

1.8-litre MZR four-cylinder with S-VT variable valve timing and chain drive — the chain being the decisive advantage over the belt-driven NB predecessors. It runs maintenance-free well beyond 200,000 km provided oil changes are kept up. Compared to the LF-DE 2.0, the 1.8 is smoother and more linear: less torque, a gentler power curve, and a quieter note. Those after NC thrills will still find them — the engine only truly wakes above 4,500 rpm and willingly pulls to 7,000. The piston-ring oil consumption issue that plagues NC1 2.0 engines from around 80,000 km is significantly rarer here; the smaller unit runs under lower thermal load. At high mileage, monitor oil level closely; the valve cover gasket and camshaft sensor (P0340/P1345) are the known wear items beyond 100,000 km.

• !! Oil consumption from stuck oil scraper rings from 80,000 km

  Specifically model years 2006–2008 exhibit extreme oil consumption (over 1 l/500 km). Oil scraper rings stick; no oil level warning fitted. Ignoring this risks catastrophic engine failure.

  Symptoms: Extremely high oil consumption, bluish smoke from the exhaust, no oil level warning
  1,500–4,000 $
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• !! Conrod bearing failure from 100,000 km

  Insufficient oil return drillings can cause oil starvation at the conrod bearings under high load. Mainly affects model years 2006–2009 with spirited driving.

  Symptoms: Knocking noise from the engine, oil pressure warning light, sudden power loss
  2,000–5,000 $
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• !! Chain tensioner wear from 150,000 km

  Timing chain rather than belt, but the chain tensioner wears. Rattling on cold start indicates diminishing chain tension. Replacing in time prevents chain jump.

  Symptoms: Rattling from the timing chain area on cold start that disappears once warm
  600–1,500 $
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+ 3 more engine weaknesses + vehicle weaknesses

2.0 litre MZR, 160 hp — rougher and more characterful than the NB engines, more displacement, more torque. Not the sharp wail of the NA 1.6, but a broader growl. The NC-specific engine problem: sudden oil loss from coked 5W-30 at cylinder 4, especially NC1 (2005-2009). Fix: switch to 5W-50 after warranty and check oil level obsessively. VVT solenoid gets contaminated at high mileage. NC2/NC3 (from 2009) with revised internals are considerably more reliable. Buying an NC? NC2 or NC3. The NC was mocked as the Fat Miata — unfairly on a country road, fairly on the scales.

• !! Timing belt — interference engine, maintenance critical from 120,000 km

  The LF-DE is an interference engine. A snapped timing belt causes serious engine damage via piston-to-valve contact. Change interval 120,000 km; always replace water pump and idler pulleys at the same time.

  Symptoms: Engine will not start after belt failure, no compression, severe engine noise on starting attempt
  500–950 $
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• !! Thermostat failure — overheating or under-cooling from 100,000 km

  The thermostat of the LF-DE can fail from around 100,000 km — either sticking closed (overheating) or permanently open (under-cooling). Water pump often follows shortly after.

  Symptoms: Coolant temperature rises sharply or stays permanently low, heater produces no warmth
  80–300 $
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• ! Throttle body dirty from carbon deposits from 80,000 km

  Carbon deposits on the throttle ring cause a sticky mechanism and unstable idle. Particularly common on the Mazda6 GG — engine stalls on declutching.

  Symptoms: Engine dies when declutching or braking, hunting idle, throttle slightly sticky
  50–250 $
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+ 5 more engine weaknesses + vehicle weaknesses