gas path
One thing the RR motor has always been good at performance retention over its lifetime. The hightime engine achieved over 40k hours on wing. The mount bolts still had the boeing seal on them when it was eventually pulled for overhaul.
Occasionally, some engines and operators achieve high time on-wing, it depends on lots of factors.
GE Aviation has recognized Kenya Airways for achieving the highest time on wing for a CF6-80C2 engine in Africa. The Kenya Airways' CF6-80C2 engine was installed on a Boeing 767-300ER aircraft in 2001 and has accumulated more than 35,000 flight hours and more than 6,400 cycles without a removal.
American Airlines has set a time on wing record for a GE CF6-80C2 engine - logging more than 40,000 flight hours and nearly 10 years of continuous on-wing operation on a Boeing 767 aircraft.