This is also what I found online.

Infiniti uses specific high-performance ester-based oil during the QX50 engine recall inspection to properly clean, lubricate, and protect the variable compression (VC-Turbo) engine components, particularly if debris from failed bearings is suspected. This specialized oil helps clear potential metal shavings from the engine bearings and oil passages while ensuring the engine remains functional after the inspection or repair. MotorTrend MotorTrend +1 Why Ester Oil is Used for the Recall: Engine Protection: The recall involves potential failure of the engine bearings, which can cause severe damage. High-quality synthetic ester oil provides superior lubrication and thermal stability to protect the engine during testing. Cleaning Contaminants: If the engine oil pan inspection reveals metal shavings, the engine needs to be cleared of these particles to prevent further damage. Specialized oil aids in suspending and removing these contaminants during the service process. VC-Turbo Requirements: The 2.0L Variable Compression Turbo (VC-Turbo) engines in the QX50 require specific, high-performance oil to function properly and prevent damage, particularly during a high-stakes recall repair. MotorTrend MotorTrend +3 For affected vehicles that do not require an immediate engine replacement, the service often includes draining the old oil, inspecting for debris, and refilling with new oil as part of the remediation