When to change engine oil?

[guffins fisherman]

When winterizing a Merc 5.7 IO, is it best to change the engine oil in fall prior to winter lay-up, or in spring prior to first splash? At first, I thought fall so as to have fresh, clean oil in there for the winter. Then I thought it best to change it out in the spring so as to drain out condensation that may have formed during the winter temp. fluctuations. Any thoughts?

[fieromx3]

i prefer to change it in fall as used oil has some acidity to it from the combustion blow by. i put fresh clean oil in it then run it for a bit to get it circulated to all seals and gaskets. moisture buid up in the crankcase isnt really something to be worried about as it is sealed off pretty well from the atmosphere except through the PCV line

[TyeeTanic]

Yes, fall is the best time. I have been told acidic compounds can be present in the old oil, and it's best to change the oil, run the engine a bit to get the parts coated up and then winterize.

[guffins fisherman]

I had a feeling that may be the case. Thanks.