As a general rule, with most jet/turbine engines, oil level check and servicing should be made within a certain "time" from shutdown. I understand we did it within 30 minutes for the JT9D-7Q on the 747. If performed a longer time after shutdown, the oil level will increase in its tank.
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If you still wish to check/service the oil, motor the engine for 30 seconds, then check the level. If there is a problem with real "increase" of oil level, then it is a leak in the fuel-oil heat exchanger.
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Happy contrails