Nissan VQ37VHR

Nissan's 3.7-litre V6 — the VQ35's larger sibling — in the 370Z and most of Infiniti's rear-drive range: G37, Q50, Q70, QX50, FX and EX.

Its distinguishing system is VVEL, and it is the first thing to suspect on this engine specifically. Variable Valve Event and Lift throttles on the intake valves themselves rather than at a throttle plate, using an actuator and a linkage assembly on each bank. When the actuator or its solenoid fails the engine loses power abruptly and often sets a code that names the system, and the assembly is expensive. Nothing on the VQ35 works this way, so a diagnosis carried over from one does not apply.

It is port-injected, so the intake-valve carbon that dominates modern direct-injection work does not apply either. What it does share with the family is oil consumption at mileage and timing chain wear — and the oil consumption matters more than usual here, because VVEL is hydraulically actuated and runs on the engine's oil. Low or degraded oil is a VVEL fault waiting to happen, not just a maintenance lapse.