No shifting until 120 degrees

[juniinc]

1991 Four winns sport cuddy wi

1991 Four winns sport cuddy with OMC 4.3 I/O.
My manual says "allow the engine warm up to at least 120 degrees before shifting into gear?
Is that true & why?
Thanks in advance.

 

[hystat]

"Why it says that:
Cold alumi

"Why it says that:
Cold aluminum pistons are not round. They are slightly oval.
Placing an engine under load when the pistons are slightly oval can damage the pistons and cylinder bores.
Once they get warmed up, the pistons become round and fit the round bores of the engine block better."

 

[juniinc]

That explains it all.
Thanks

That explains it all.
Thanks much Hystat.