What people are missing is that the OP is asking about switching between a “premium” tcw-3 standard oil and the premium plus synthetic blend. Not the same oil. As BCB and CoosaCat stated, run the old oil out as much as possible then switch. It does tend to clabber or gel at the bottom of the reservoir if it sits.96 Eyra/12 Mercury 175 Pro XS with 2015 single axle trailer2017 Victory Gunner
