Mercury Racing 525 EFI
 

Looking at 2011 with a 525 EFI and 17 hrs. How reliable is this engine? What is the maintenance schedule? I'm currently running a 496 Mag with 300 trouble free hrs.

Great engine. Ran twins in a 33 Daytona with 160 trouble free hours. We changed the oil every 15-20 hours.

17 hrs is barely broken in! You should start to think about going through the top end at around 250 hrs. The real weak link in that package is going to be the CMI headers (lots of info on that subject on this forum). Like tjred said, change the oil often (I did mine every 20-25 hrs) and keep an eye on the headers and you should be good.

Are you swapping out your 496? You will want to look to upgrade the drive to an XR to handle the extra HP.

2011 Would have the "Generation X" CMI Headers which should be no problem.

no, this is in a bigger boat. I read about the header issue, thanks Perfect Storm for clarifying the gen x headers. So forgive my engine ignorance but what exactly is involved with a top end rebuild? The boat has an XR drive as well.

Wrong!. Gen X headers have the same so called "cool collar" design. The weak spot. Gen X headers have a "turn down" part at the collectors, to help "back wash" and reversion. And that does help, but the rest is pretty much the same as the "older" stuff. Flange/tube connection area is the weak point. AS far as the 525's, great set up, keep an eye on the headers and at the head/flange connections. Oil cooler, PS fluid cooler, heat exchanger, all have a "strainer" like part, full of holes, where "stuff" could get stuck and increase engine heat or lower water flow. Just watch it, and clean periodically.