Changing oil and engine idling after long trips?

Highway miles are easier on oil, as others have said. Short trips (particularly in cold weather) are the hardest on oil. I wouldn't change your oil until the normal interval.
As far as idling before driving off and after stopping, 10-20 seconds is really not "idling". Idling before shutdown is solely to cool turbo, idling for warm-up is generally considered a waste of fuel, and prolonging the engine from getting up to temp. That said, I personally ensure my vehicles are somewhat warmed up prior to being placed under heavy load (towing, plowing, interstate, etc).

GoPackGo wrote:
Are we talking diesels ??

My F350 diesel owner's manual states to let the beast warm up for a few minutes before putting it in gear and I do. And I ALWAYS let it idle while I hitch up in the morning. No way will I make a cold motor pull my 9000 pound truck and 14,000 pound rig up the ramp and onto the interstate.

If a turbo motor, you will want to let it idle for several minutes before you shut it down after you pull off the highway. This is important.

Highway driving is generally better (and easier) for an engine then running around town. It gets up to operating temp and stays there for long periods of time. This burns off all the deposits and also water vapor that is generated during the combustion process. Cold engines don't do a very good job of this. Short trips of less then 5 miles are really hard on engines.

Don't need to change oil early - change it at the mileage specified in your owner's manual.

I agree on the warm up. I never put a big load on my TV until it has warmed up. The process of hooking up is a good time to let it run.

Are we talking diesels ??

My F350 diesel owner's manual states to let the beast warm up for a few minutes before putting it in gear and I do. And I ALWAYS let it idle while I hitch up in the morning. No way will I make a cold motor pull my 9000 pound truck and 14,000 pound rig up the ramp and onto the interstate.

If a turbo motor, you will want to let it idle for several minutes before you shut it down after you pull off the highway. This is important.

Highway driving is generally better (and easier) for an engine then running around town. It gets up to operating temp and stays there for long periods of time. This burns off all the deposits and also water vapor that is generated during the combustion process. Cold engines don't do a very good job of this. Short trips of less then 5 miles are really hard on engines.

Don't need to change oil early - change it at the mileage specified in your owner's manual.

Humor me, what are you driving?

Idling prior to driving is just wasting fuel and is not needed
Idling after driving is OK. Allows turbo to cool so that oil isn't cooked.....IF you have just finished a long hard pull. Otherwise that is not really needed either.

Oil change....follow you maintenance schedule in owners manual for your rig
Most are 7500 miles or more these days