I know that citgo was making it for yamaha,mercury,omc, I think honda but not positive. they were not all the same oil.each manufacture has defrent problems that need a defrent blend. yamaha had wrist pin problems in the 90"S mercury had bearing& ring problems,omc had piston gualding problems.& the wallmart brand marine oil was killing all three types of engines. just because it has all the specs dosent mean it is any good. so if there are no major problems It's probly not to special.I will be useing castrol edge full synthetic. I used mobil in my montaro that I just traded for my E.because the oil pressure was getting low.&a few years back I seem to remember the faa pulling mobil from aircraft use. + my montaro was getting sludge in it.synthetic is not supost to do that.3000-4000 in between changes. always used kendall in racecar, castrol in street car mobil in car. I think it will be castrol&kendall blend in my E . since the introduction of roller cams in everything produced now the oil has changed a lot since 1984( I think thats the year) no more zincdisomethen or another.for the flat tappets that slid across the cam. (epa also wanted it gone&that helped it to go) so if you have an older car like my vw bug,or 340 duster,YOU NEED TO USE AN ADDTIVE,or "snake oil" pro blend,redline ,lucas ,any of the major manufactures will usuly do fine. try to staway from teflon in greese or oil addtive.it can and will kill needle&roller&ball bearings. if your old chevy or ford dosent have any ball,needle roller bearings (mostly in roller rockers)it will be fine & is actuly good for older rod&main bearings but dont use if you have a oil cooler of the plate type they can clog it & cant be cleaned out very well. the greese can kill ujoints,wheelbearings etc.(the teflon as small as it is it can take up the clearance & kill the bearings)I think that is why you dont see slick 50 to much any more.