That's all i use anymore since i started using it i've found my motor's don't load up of gunk up near as bad. read the bottle for there brand it take's more of it to do the same as others. I've used Pennzoil and it's still Avail at Advance Auto stores. Pennzoil and Walmart both seem to mix and run the same both are good oils in my opinion. Quick Silver is harsh on motors i've opened up some that ran Mercury's oil. um it gunks them up and makes the rings full of carbon and sticky. It's like Quaker State in a 2 stroke version. Tar oil lol. if you want the best by far and want synthetic buy Klotz Oil
http://www.klotzlube.com/storeProdDetails.asp?pi=29
I use to run Klotz Synthetic Purple Preminum in my Race Standup Kaw Jet Ski. It would give you 4 to 6 MPH on the 575cc motor. It topped out at 74 MPH WAO.