The colder it gets, the longer I let my equipment warm up before use. Cold oil combined with a cold engine is a killer. I read a report on tractor trailers that use engine oil preheaters. They said they could get something like 40% more life out of an engine if the oil is preheated.
What I really don't like doing is moving my ZTR with ice cold hydros. I may put a preheater pad on the tank to at least warm up the oil. It's a 1.5 gallon steel tank so a pad should work fine.