My '07 Coablt 252 now has 35 hours on it. I have never used it to pull any water toys.

I've had to put exactly 1 quart of Mercury High Performance Gear Lube in it during this time and the reservoir is near empty again. Does this sound normal?

How much do you guys use? Please state engine, drive, and boat model combo.

My Cobalt dealer says it's normal. My boat storage facility and boat launch service says it's not. My boat storage facility is a Mercury Authorized dealer and service center. I'm not sure who to believe. Maybe I'll at least get the dealer to let the Merc service center check it out (1/2 hour diagnostic labor) or something.

Sounds excessive to me. Agree that it is a good idea to have inspected for a leak.

Any signs of lube in the bilge?

NOT NORMAL!!!!!

If gear lube can get out, can water get in?

Have the pressure test you lower unit.

The put a slight positive and then a slight negative pressure to verify integrity. That's what they did with my VP when I was told it had water contamination.

That's excessive. What type of fluid was already in there? I ask this because I once put Pensoil Marine synthetic gearlube in my outdrive and I went through alot (maybe a quart). It was thinner than Mercs outdrive fluid. Once I put Mercs stuff back in, I didn't go through much at all

Mine has never lost any fluid

Sounds a little high. I put about a pint of lube in the resevoir of mine in the first 25 hours, but after that, I've never had to top it off.

Definitely have it checked. I have the same engine and drive combo and have not had a problem. Kind of odd I haven't had the same problem. I am the poster child for "if it can go wrong, it will go wrong".

It depends on weather it was filled correctly. I have changed my Bravo one and Alpha one and sometimes it stayed filled and sometimes I have to add a pint or two. If you fill to fast you will have bubbles in your out drive till they work up to the top. Hence no leak only missing lube.

I have to add lube to mine from time to time, but not 1 quart in 35 engine hours.

On my last boat,02 w/6.2 B3, they told me some usage(?) was acceptable.Sounded like BS to me so I started pushing hard and
found that at times Merc has metallurgy inconsistencies and propshaft seals were cutting grooves in the shafts and loosing
oil there.$2700.00 repair, say "thank you extended service plan".
So push hard for the truth, mine started early and ended up loosing
a resiviour full every outing.

Sounds like you definitely have a leak someplace. You really should not "use" any, unless you have a leak, it has nowhere to "go".

either that or, as said, it MAY have not been quite full, but a quart sure seems to be a lot.

How much GL-5 goes in you guys typical drives?

My jet only uses about 1/2 pint, from dry.

Same here. The second time I took it out, I noticed it was low and had to go buy a quart at the marina so I could top it off. I've used a little under half a quart in 80 hours.

Just about 2 qts in a Bravo 3.

I'm having what I feel is excessive use of gear lube in my port drive unit. No leaks to be found in the engine compartment.

Working with dealer on the issue and will have it inspected when the boat is pulled out in a few weeks.

Does anyone know IF there is a leak, will the gear lube appear "milky" in the lube monitor or not ?

Curious to see what the condition of the lube is like when it's changed.

Also, if the proshaft seal is leaking, will the actual prop shaft be damaged or is it all internal??

F-Fan, you can have contamination and it won't show in the reservoir for a while since there isn't any recirculation to speak of. You can also have a leak and not have any contamination due to the way the system self pressurizes due to the fluid expanding when it heats up.

A bunch of the B-3 owners I know tell me they use some fluid during the season. While I'm envious of the folks who have "tight" drives, I don't lose any sleep over the little bit I have to add every few times out either...it's always been water free when I've drained it.

Exactly my experiences as well.

DaveR once posted on here about the 2 way seal on a B3 drive. The gist was that it's possible foe it to let oil out, but not water in. Since I add oil to mine periodically, but have never had water contamination, I have to believe he's right on the money.

That said 1 qt in 35 engine hours seems like a lot. Unless the drive wasn't properly refilled when serviced.

I recently brought the same issue up on another board and most explained to me that some usage is considered normal, specifically when new due to possible air in the drive and fluid filling everything. Also the only time that I notice any use is after long hard runs 2-3 hours at 3800 to 4200 rpm trying to get somewhere. On thing you may want to do is to check all your bolts on the drive to make sure everything is tight. I discovered my top cover bolts loose and when the drive was warm I lost some fluid due to expansion. Have it pressure tested and keep an eye on it.

Well, my mechanic pressure tested the lower unit and they left it on for approx 24 hours straight. The needle didn't move the one bit.

At one quart which is the same as 2 pints and a 24 hour pressure test, I feel better and will just continue to monitor. I may ask them to pressure test again during winterizing.

I wonder if draining all the fluid out and then pressure testing would make any difference?

I don't think it's unusual.

First 1 quart was probably mostly due to air pockets. I don't know, but I'm betting they don't take the time to fill them from the bottom to the top like you're supposed to do. (don't know if that's done at the factory or the dealer). Anyway, they hold 3 quarts total.

My 496 B3 used about a quart in the first 10 hours. Since then, some, but not excessive use.

The reservoir is only about a 1/3 of a quart - so that wouldn't be much in the first 35 hours.

It was almost exactly the same with the Alpha on my other boat.

Fist 70 hours on mine this summer. Was still at the full line before I changed it last week. Since yours past the pressure test I would say an air bubble.



My Volvo duopro uses 2.5 quarts.

Don't know about Merc's, but my VP SX has the same oil level as it had the year before when I changed it(after six years and 280 hrs. Usage essentially zero.

Mike