I had analysed a sample of engine oil from a car sitting outdoor for more than 10 years. The results show that the oil characteristics are still excellent.
https://bobistheoilguy.com/forums/ubbthreads.php/topics/4562503/Re:_Are_modern_engine_oils_tim#Post4562503
https://bobistheoilguy.com/forums/ubbthreads.php/topics/4562503/Re:_Are_modern_engine_oils_tim#Post4562503