90w lower gear oil change- 2011 honda 225hp

DO NOT use the "sucker" on that gearcase! You risk damaging the seals and causing a leak and water intrusion. The gearcase is sealed against a small pressure buildup as it heats up and a VERY small negative pressure (slight vacuum) as it cools down. Over pressurizing the case, one way or another, can lead to an expensive repair.

You could opt to drain and refill with the outboard tilted up as little as possible. You won't get a complete drain and fluid exchange but something is better than nothing.

While many don't adhere to Honda's recommended maintainence schedules and feel it's ok, I would generally not push it over double the prescribed interval.

I would not recommend going ONE hour over the interval if this is a new gear set. When machine parts are put into service for the first time, rapid wear can, and does, occur as the various contacting components "wear in" to each other and become a true matching set of working parts. It is important to get the metal debris that develops during this "break in" period out of there asap.

When you can't get a full drain, you can do two "partials" , in rapid succession, and get quite a bit of garbage out and clean in until the trailer becomes available to do it properly.

Your call.

Good luck.

And a partial will show you if the oil is milky and contaminated.

The Merc oil should be fine.

How much will you use it in the next 3 weeks? If not much, drain a little to see if its milky or watery, if not, just leave it alone.

If milky or watery, drain it and refill, as the old contaminated oil and water is not good for the metal etc. in your gear case.

Totally agree with Jimmy. I answered your questions in more detail on the maintenance forum on this site. Will repeat here for others.

Bondo is correct. It's really not possible to change the lower unit oil adequately without access to the bottom and top of the lower unit. The unit must be filled from the bottom while in the vertical position. Otherwise, air will get trapped in there and it will lack sufficient lubrication.

The change interval on the 225 has a lot to do with how old it is. New engines should have the lower unit oil changed religiously every 100 hours for at least the first 500 hours. After that, it's OK to spread it out to 200 hours or more. The reason for that is that once the lower unit is well broken in, there are (or should be) very few metal flakes that are released from the gears.

The lower plug on that engine is magnetic and that should be inspected carefully on each oil change. If it has any metal flakes much larger than talcum powder after break in, then it's signaling a problem in the lower unit.

Also agree that synthetic is the way to go with the lower unit. However, I don't waste money with synthetic on the engine oil because it should be changed every 100 hours, regardless.