Re: Engine oil #2 (full synthetic)
I'm not a lubrication engineer, but the sum total of what I've heard is that you have to worry about both mileage and time..
If you run low mileage because you only do half a dozen long trips every year and otherwise leave it in the garage, then the time isn't so much an issue..
but if you run low mileage because you mostly do two miles to the bagel shop and back, then you never get the oil hot enough to evaporate the water and other stuff, and you need to get that stuff out of the crankcase on a 4-6 month schedule.
and, at the end of the day, there is nothing wrong with pampering your vehicle.
2007 WK Limited 5.7L
2014 WK2 Overland 5.7L
And a few past Durangos