I got my drive lube analysis back from the lab and the reading is showing some 3000 parts per million (0.3%) with 1500 being the warning level. This is not visible to the naked eye as the lube looks fine. The lube was run for 60 hours over two seasons (I don't get out as much as I'd like, but oh well). There was also a bit of iron showing up (~125 parts per million). All other wear metals were below the advisory level.

How much water is too much water?

Where does it typically get in? (Drive seals?)

Do I have a problem?

Is there a better lube to use than the Merc straight 90W?

Before you rant on me, I know. I will be cutting the interval down to 30 hours and not more than one season.

For the application, I tend to think you will be ok (no damage). 2 years is a long time for the environment it is dealing with so definitely do the 1 year change.

D

Agreed, but it was only run 20 or so hours in 2006, so I thought, WTH; why change it. guess I was wrong.

Still, is there a better lube to use than the Merc straight 90W? This stuff is a 60 year old formulation using Group I base stocks. Synthetics are considered Group III or IV.

Deep, you should change your gear oil every year, no matter how few of hours you put on it. Same with engine oil.
Why, oh why don't people get that point? (You are just the latest in a long line, so I am not calling you out.)

Yep. I've changed the engine oil every season, but not the drive oil. This sat for four months in the drive and also for two months in the sample bottle as I was lazy in sending it in. Some of it is attributed to condensation over that time due to it not being drained hot and right at the end of the season. This year, I'll be doing it in the late summer or early fall.

Any thoughts on using better quality lube?

Doesn't Merc or Volvo have a semi-synthetic lube?

I always used Merc's HPGL. It's either synthetic or semi-synthetic. Can't remember which.

3000 parts per million calculates down to 1/2 teaspoon of water to 2.6 quarts of lube. I wouldn't call that much water divided by your hours excessive, but IMO that IS excessive in your drive AT THE MOMENT...

The lube is not in the drive now, It is in some oil recycling plant, I think.

Where does it get in?

Propshaft seal tends to be the biggest culprit of water intrusion.

Just curious, what caused you to have this analysis done in the first place?

I'm thinking a synthetic or semi-synthetic lube would do a better job of lubricating in the contaminated state. That might help protect the drive some.

I'm betting water gets in from temperature changes within the seals. Hot air to cold water, etc. Then there is always the absorbing from the tank and condensation, etc. 2 years is a real long time.

I do it as a matter of course on my truck and I just thought I'd give it a shot with the boat.

I would recommend AMSOIL Marine Gear Lube 75w-90.

P.S....I'm not an Amsoil dealer

I also run the Amsoil stuff in our drive....and change it out every fall.

You might want to have a pressure and vaccum test done on the drive. That will tell you if there are leaks that you need to be concerned with. I use Merc's high performance gear lube in my Cobra as per my mechanics recommendation.