I have a 2007 Win. Adventurer. In May of this year w/roughly 19,000 miles on our coach I switched over to Mobile One 10W - 30W. Left on a trip to Nashville over a 2 week period and went through 3 qts of oil on the trip, not bad. Changed oil and lubed in Nashville and started to head home via Bourbon Country. Somewhere about Kansas I started having intermittent oil pressure issues meaning lifters starting to click. Backed off the throttle and the issues went away. It slowly got worse as we got closer to the Oregon Coast. The last hill I climbed was at about 10 miles an hour in first gear and 1800 rpm. Puzzled we were, was it a spun bearing, not for that distance, Oil pump failure with 26,000 miles, doubtful. So I could not find anything online or in forums that really addressed this issue, though someone here got close. Conventional oil builds up sludge lets call it, each time it gets hot and cools down, as well as when it sets for months without being operated. Bet you can see whats coming here. You also need to know that a gear pump, which almost all engines have today, will continue to build pressure unless something gives. So I questioned if there was an oil cooler bypass, which there would have to be if it plugged and the oil had no other place to go, meaning it would blow up if not bypassed. And Wallah, the oil filter housing is also the bypass for the oil cooler as well as the filter itself. I had a truck Mech. in the Portland area research that issue and sure enough the oil cooler lines where full of sludge. The moral of this story is switching from Conventional Motor oil to Synthetic can be a little tricky. No damage was done because I listened to what the engine was doing, sounding anything but NORMAL. We also added an external oil cooler as well. Travel well my friends!