Rat,
Let me tell you this about that..
For a some of my time in the OE, I ran the engine tear-down and inspection room(s). At that time (20+ya) that manufacturer was calling for a 7500 Lube Oil Service interval. It was SOP for the proving ground to run X2. I never saw lube oil related failures that were not first material failures.
The real problem with modern engines and long service intervals is not that the lube oil gets worn out (new oils are amazing in this regard) but that short cycling fouls the oil with moisture and other combustion by-products. the biggest problem those present is corrosion.
Now, you are going to switch to a synthetic, good move. There are two benefits to synthetics. First is temperature breakdown resistance. I suspect that will not be a big issue to you. But the other is the resistance to the formation of acids that can lead to corrosion of the oil wetted components. Unfortunately, you will not get the full benefit until after the next oil change. It takes an extensive procedure to get even 90% of the lube oil out of an engine.
As you will not be short cycling the engine during this excursion, you will be in good shape.
Matt
Matt & Mary Colie
A sailor, his bride and their black dogs (one dear dog is waiting for us at the bridge) going to see some dry places that have Geocaches in a coach made the year we married.