How often do you change yours? I usually do every other season. I have a Mercury 150xr6.

Every time my motor goes below 14 lbs at full speed. Mercury's minimum is 12 but I like to see it higher. Sometimes as short as a couple months if I run it in mud.

Is it a hard thing to do? (new boat owner here)

My first boat (2003) Merc hasn't been change and still running strong. My 2012 hasn't been changed either at this point. Don't know if I want to tackle it on my own when I decide to have it changed.

Was told rule of thumb is every two years unless ran in brackish/salty water and then every year best. Youtube changing the impeller, you will see how easy it is to do yourself.

Every other year, its cheap insurance,and no ,absolutely no dry cranking, ever

i go with the pressure rule. as long as i'm gettin 15+ lbs, i don't worry. this one i have now is 6 yrs old and still pumpin. i really believe that sitting for long periods of time is the worst thing for a impeller. if you use the boat regularly, they'll last a lot longer. JMO.

There not really hard. But I wouldn't say the easiest thing if that makes any sense. Just take your time and have a helper. Two key things are lining up splines in shafts going into flywheel at top and the shifter coupler connection. Best way I've found is to have motor cover off and if it doesn't want to go up have someone rotate flywheel a bit then you'll fill it align and come up as you put upward pressure. If you don't hang an OEM Mercury manual I would get one. It's a must have if you plan on doing your own work.

If you acquire a new to you boat, the very first thing you should do is to replace the impeller, or at the very least inspect it.
It is not only about moving water, it is the residue and pieces of rubber from an old or worn/damaged impeller obstructing or clogging everything up.
When it comes to pump impellers, if you wait until it needs to be replaced, you waited too long.

No, not really. There are a ton of YouTube videos showing people doing it. Watch as many as you like to see if you are comfortable doing it. Go slow, take pics as you pull things apart, change it, and put it back together. One of the videos recommended a very light coat of marine grease inside the housing so that it was lubed on initial start-up after the change. I followed that advice. I can tell you having one of the Black and Decker workmate tables helps. You just open it up and the skeg goes right between the two pieces and it holds it steady.

For schedule, I'll follow an every other season one whether it needs it or not. Cheap insurance, and in my younger days I didn't know what an impeller was and burned up a 50 horse. Lesson learned.

I replace mine every year. Probably the best "just in case" money you'll ever spend on your boat.

I agree with everyone else that you'll want to swap impellers more often than not, i.e. every 2 years max. On the other hand, I just changed mine and it was at least three years old; but the old one was in near perfect condition (see pic here). So those things are pretty tough. I rarely dry start the motor and avoid running in muddy water.

On mercurys you're suppose to replace them every year.

On my Merc 150 Optimax - it must be replaced every two years, or your in trouble! For some reason the rubber deforms quickly and even looks almost new - but it wont build pressure sufficiently. Cheep insurance is to replace it.

There is no set time. Too many variable's. Good insurance. Guys that fish a lot= every year, others every other year. Watch your water pressure.