After an average of 45 hours my drive oil comes out clean and green. I'm not running crazy power but it is a Bravo XR. I guess I don't have to worry.

Zgoo I see what you're saying...., but ithink we are comparing grapes and watermelons.

It was a catchy title and i was hoping i could chime in by saying i am making my drives last forever by not taking my boats out much .
Cant speak for the volvos but the merc green does a swell job of punting the water,if any ,and any heavies down to the bottom . So i do like to make a habit of doing a monday drive drop and a friday morn plug pull more than most just to have a little peek at whats going on and if i need to peek more.
Back in the plymouth fury days and ww2 stp oil treatment was all the rage to stretch those oil change intervals way out there .
The gear driven cutters and eqt i have runs a very clear synthetic 30w that yes ,does have a uncanny ability to get any rouge metallics straight to the bottom of the sump.
certainly isnt going to hurt the life of your drive but your going to have to do a oil analysis of some samples to know how much impact your really having on the drive .

I get the point of the OP's post & it makes for interesting discussion.

The gist of his argument if I understand it correctly is it's better to constantly "refresh" the oil than let it get to the point of essentially no protection and then change it out.

The hypothesis can probably be broken down into a math problem taking into consideration volume, use, time at different percentages of "goodness" of the lubricant, angle of dangle, etc etc.

However, coming up with a comparative formula that accurately takes all the factors into consideration would 1) give me a headache and 2) cut into my beer time.

To me, where his argument fails, is that it's based on the premise that one lets the drive oil get to that state of "no protection" prior to changing.

That might work with a stock, low hp setup where annual changing is sufficient, even if less than optimal.

I don't do that. We live in MI and I'd much rather do the maintenance and change things on "my" schedule that risk losing the majority of our (short) season waiting on parts or repairing a drive that puked.

I change the drive oil before the boat goes in the water.

We run it every week and if I've been "easy" on it using my less than scientific standards I don't worry about it other than checking the level.

If I feel I've been hard on it I check the magnets and depending what I find may drain a bit of oil through a white filter element looking for "bad stuff". If I find "bad stuff" or the oil doesn't look brand new, I change it.

If I've run 80+ I change the drive oil, even if it was changed last week.

I go through a lot of drive oil

I'm the least mechanical person I know and it takes less than an hour and a couple beers to do.

In my opinion it's just part of the deal if you're going to run big HP through an XR drive but opinions are like mailboxes and your mileage may vary.

Cheers

s

And it is best to drain all the oil and pressure test the outdrive bare min once per year. it is always best when storing (layup) your boat to have all fresh oils in them completely and topped off.

I knew that when I first posted I would get a reaction but it's all good, It just makes us think about things in a different way. BUP I was just wondering if you change the oil in the drive and pressure check at the start of the year, at what hour of use does the drive start letting water in the drive oil, hour 1 or hour 40??? We are told to check the engine oil every time we run it, but the drive is set and forget, nothing to it as drives never break or needs work??? If we drained a bit of the lower oil out of the drive and every 5 or what ever works for you hours,check for problems and always added more clean oil, just seems to make sense to me. BUP on a side note, should the drive be checked for alignment every year on a stock 496 Mag HO and XR??

I don't know about this oil theory since we all know that oil company wants us to keep buying oil, but i can add comment on BUP's comment over water condensation in cars exhaust.
Do you ever see water comes out of car exhaust in warm weather? I don't, why? because water doesn't come out of combustion chamber, actually condensation happens in exhaust itself when hot exhaust air travels thru the cold exhaust that's surounded with cold outside temperature and condense water starts to collect in the muffler and exhaust pipe...

I do now. Been talking about this since ethanol became the standad gas around here.

Water just pours out of the exhaust after sitting over night.

This only happened when cold and/or cold and humid.

Not anymore.

Been replacing a lot more newe car exhaust than before.

I study/repair cars all day. I see this schit. LOL.

One of the things I have done as a career is work on large steam turbines and 800 to 1500 hp air compressors. We send oil out for testing and get analysis reports back. We clean strainers AND filters on a maintenance schedule then we can also hook a centrifugal clarifyer and filter /recirculate the oil to remove moisture and contaminants. NOW here's the thing, these things hold 250 to 1500 gallons of expensive synthetic oil, they have no combustion gasses contaminating them either so there is a REASON why its not just changed annually or every so many hours. Now on my personal boat, when I drain the drive oil I used to get metal particles out, I now have a external cooler and recirculating pump on my Bravo , I used to change oil every 10 hours or so, started out with much longer intervals than that BUT I found where it just starts to go bad and get contaminated and thats where I changed it. Now that I have the filter on it I change and cut open the filter every 10-15 hours and IF its clean I top it off and continue running it , I have been getting 30-40 hours from drive oil but it also no longer gets burnt having a heat exchanger type cooler on it. Would I keep topping off the oil in my car engine and keep running it, NO. With proper filtraation and cooling you could extend the oil life in your drive which is what I have done, fwiw, Smitty