Really depends how cold... Usually 10 mins is enough to warm the engine. Id still keep it lower in the RPM's for an extra 10 mins or so. Id use a lighter weight oil in the winter though. Helps lubricate things "quicker". Anyways, 10-15 mins is a good amount of warm-up time.
How long do you need to idle in the winter before your comfortable hopping in to drive?
Is 10 minutes a good amount of time to get to a decent temp?
Really depends how cold... Usually 10 mins is enough to warm the engine. Id still keep it lower in the RPM's for an extra 10 mins or so. Id use a lighter weight oil in the winter though. Helps lubricate things "quicker". Anyways, 10-15 mins is a good amount of warm-up time.