[Legbreaker]

The 8th in my proposed scenario aren't the ones that will do the extraction - that's to be done by engineers and equipment brought in by sea once the area is secured.
It's also possible the plan could have involved using local manpower and skills to do the job.

The 8th also didn't make it to the shale, the navigational error (more minor than presented in the book) along with a few other "hiccups" along the way left them a little short of the objective and nothing but fumes in the tank.

Once processed, the oil could be shipped back by sea. We know the Marines were moved into Northern Poland that way, and the same ships could potentially be used. Even if just the unprocessed shale itself was shipped, that's probably more than Nato had available before the offensive. It could then be processed back in Germany in plants constructed over the previous year.

The 8th themselves probably wouldn't need much of the oil for themselves. Being relatively stationary and tasked (once arrived) with defence of the resource, locally produced alcohol might be enough for most of their vehicles - only their aircraft would need the oil based fuels.

Roadsigns in a war zone? As in England in 1940, the signs were probably removed to prevent the enemy using them to navigate by. Locals are few and far between, and may, or may not tell the truth. Prisoners would likewise be untrustworthy as sources of navigational intel.

There's no way a single navigational mistake is going to put them 200+ km off course. That's a given. It would though put them 20-30km off, possibly more if the maps were dodgy and the weather foul.

It could be that the Soviets are indeed exploiting it, to the limits of their abilities anyway. Don't forget that they have the far more readily available oil from Romania to use though, so shale oil is less likely to be a priority for them. It could also be that the locals have carried on regular sabotage of the facilities, or that the necessary transportation infrastructure has been destroyed (and processing facilities are somewhere back in Russia).

Perhaps the 8th were not expected to take the resource all by themselves? Maybe the 50th AD, 116th ACR and Canadians were to follow on immediately but instead got bogged down when the Pact counter attacked quicker, and harder than expected? It could even be that the Marines were to re-board their ships and move around the moment the Germans caught up and relieved them?

Without the Pact being weak in the north of Poland, the entire offensive is extremely unlikely to have occurred. This weakness could actually have been part of the Pact plan - lure Nato into attacking through this corridor then slam the gate shut behind them, cutting off at least XI Corp and hopefully all of German III Army before pushing them into the sea?

It may not even have been the shale they were after, but some other resource, or collection of resources in the area. Oil shale just seems like something worth fighting over in T2K.