Castrol synthetic or Valvoline?

Almost like the oil has broken down to much and is causing to little resistance or more

Sorry to say that, but that is utter BS. Oil doesn't have a lifespan or expiration date. Sure it slowly breaks down over time (mostly from heat) but not after just a few 1000 miles.
They have run tests with simple standard motor oils and let it in the engine for, say, 50000 miles. They just topped it off when required. After that they drained it (being pitch black then) and had it analyzed. It was still oil and was still doing its job, it had degraded but not that it would have hurt the engine. That was in the 1990's, and we have much better oil available today.