Engine is a 2009 mercury pro xs 250 horse. 

 

For the past two seasons I've used quicksilver premium gear lube 80w-90.

 

I just went to grab a bottle out of the cupboard to look at changing it today, but somehow I've never noticed in little black letters on the bottle it reads: 

 

'For use in all outboard lower units and get pumps BELOW 75 hp'.

 

Any chance the lower unit has been damaged by this oil? What oil are you guys running in bigger engines?

 

Thanks

That does not sound like it can only be used for below 75hp, but can also be used for those engines, but let's hear from the Merc users.

The 80w-90 works as a lighter oil when cold, the 80 part, and the additives make it work like a 90 when it gets hot.  Your motor most likely needs a straight 90 but I would doubt you have done any damage running the 80w-90 for a few seasons.  Some people don't change the oil, that's where the damage will happen. 

Should use what is recommended Mercury High Performance SAE 90 lower unit lub for hp over 75. There is a warning not to mix SAE 80W90 with SAE 90, so drain the old lub thoroughly.

Tom

It's still in one piece, so you haven't totally ruined it.  Unless you run full throttle all the time or make extremely long runs full throttle a lot, I actually doubt you've even harmed it.  The High Performance 90W is what you should have been using, but that's in the past now.  Get the right stuff, take both plugs out and just let it sit for about a day to give it time to drain all it can out.  Then fill it from the bottom, pushing the oil up into the LU until it comes out the top.  Put the plug in the top, then take the pump loose from the bottom and put that plug in as quickly as possible.  Make sure to put the top plug in first to limit the amount of loss when you disconnect from the bottom.

 

The main concern is the heat those LU units can build under the stress of those big motors and sustained high RPM's.  The 80W90 can start to break down and loose most of the protection from metal on metal when it gets extremely hot.

Likely haven't done any damage but needs to have the straight 90 weight oil. Local wal mart's sell this as well as what you've been running.  I'd just put the 90 in it and not worry about it 

80w90 and 90 weight are the same viscosity once up to operating temp, the only difference is the 80w90 flows better when cold. 

Doubtful on damage if you haven't been experiencing malfunctions or odd behavior. That being said, you should switch to the appropriate oil for your motor class to protect your lower end for the future.

It's not all about the viscosity of the lube.  It has more to do with the additives in one versus the other and molecular structure of the lube.

So did I mess up? Got a decent day out today.  42 out right now, high of 60 so I decided to crack the lower unit and going to let it drip all day. 

 

Upon first opening up the lower unit im not liking the color of it. This pale blue oil has settled at the bottom, more it drains the darker it's getting. Is this water that has gotten in or the oil breaking down? Dummy move I didn't replace the screw bushings last year, already got new ones ready to put on this year. 

 

 

I confused, which is easy for me with Merc's, but where is that stuff draining from.  It looks like it's draining out of the exhaust port at the prop end.   Is that where they put the drain plug on those?

As for the color and what it's supposed to look like, don't know, never used Quicksilver lube but somewhere I've heard it's blue, so don't know what it looks like when you drain it.  That may be totally normal, one of the guys that do regular maintenance of theirs will have to say. 

I know that doesn't look like anywhere near enough, I would think there should be somewhere around 40 ounces in there.

@Way2slow You got it, they place the lower drain screw by the exhaust port. Have to remove the prop in order to drain it. The picture probably looks confusing, but I have a drain pan there. The little circle you see with the oil is actually the hole the oil goes into of the portable container. 

 

As far as the color of quik silver,  if you look at my above photo, you'll see a dark blue oil in the inside of the puddle. Surrounded by my questionable lighter blue oil. The dark blue is what it looks like coming out of the bottle.