Have a L67 3.8L Supercharged engine that has now had religious diet of 0W-30 XD-3. My question is that I have prolonged the oil change and coming up to 15K KM so far.. finally had new schedule that I can make it to pick up XD-3 @ Esoo, but they're out for another week or so.. so I placed an order.. I probably will get another 1000km or more by the time it actually gets here.. I don't want to do a UOA as by the time it gets back to me to let me know.. it's going to be roughly bout the same time I get the oil. So the consensus is.. wat should I do? Leave it in till I get the good mojo? Or just replace with Walmart Synthetic for now and then switch back to good mojo after?