I have a pair of the same...used the wrong oil in one and blew a powehead...(or at least that may have been the cause) Use the merc stuff or at least the recommended TC-W3. Around here (Florida) I am paying around $70 for a 2.5 gallon jug of TC-W#, and the Quicksilver (mercury brand) is around $80 at the local boat store chain. Pricey, but powerheads cost a heck of a lot more..
one engine has 1000hr, the other new one about 100. They push my 30' RyboRunner at 28knts burning 20 gals per hour total. 'To the stops' the boat will do around 32.
With the stepped hull I get unbelievable holeshots with 3 blade props...it'll get up on the plane in 3-5 boat lengths....not bad for a being heavy boat with a full tower.
I have heard that 4 blade wheels add better thrust with less chance of cavitation...but a slight loss of top end. I haven't had a problem yet.
All in all I like the motors...although they are louder than 4strokers, they are a heck of a
light lighter.
If the boat doesn't have them, it would be worth getting the smartcraft guages to replace the 'idiot lights'. these guages give a lot more info about fuel burn, alarms, temp, pressure, etc... about a grand for a pair installed, buut well worth it!