No. I use whatever brand is in the box at the time of need.So do you alternate a gallon of xd 50 and then the Pennzoil?
Both are semi-synthetic oilsThese are synthetics we are talking about correct?? IK thought the whole idea of using a synthetic was to reduce carbon..?? So why an additive?
IT's very hard to believe that Evinrude E-tec oil for example, will do anything better than regular synthetic oil will do. Outboard companies have always tried to get the public to buy their brand. Most different brands of a lot of goop sold by different companies are the exact same thing. A guy did a through test of penetrating oils on UTUBE and break fluid did as good as any of them and some of the "name" brands did not do well. Go see it yourself as it is illuminating.