lubedude i have 1997 115 v4 90 degree with vro hooked up.i would like to switch from my xd25 oem oil to a synthetic.I can not get synthetic Pennzoil for outboards in canada.I can get shell nautilist synthetic apparantly Shell Oil owns pennzoil? might be the same oil in a different package?.Do i have to drain my oil tank or can i mix the two when the level gets low.the package says nothing about remote oil mixing,just gives pre mix amounts.Thanks Scott