Sportmaster oil fill level practices?

[river rocket]

Put 28oz in it like the manual says. Or keep putting more in and buy the vent kit. the manual says 28oz for a reason. I filled all mine to the spec in the manual.

[Captin Hazlewood]

I just filled mine, and it took 44 oz., until it just barely comes out the vent hole. I would have to drain 8 to 10 oz. to get to the 34-36 you recommend, and drain 16 oz. to get to the 28oz factory spec!

I didn’t recommend 34-36 oz. I recommend filling until it just barely comes out the vent then drain off a couple ounces. I honestly don’t know what mine holds but I do know it is more than 32 oz.

[Sleek Jr]

I didn’t recommend 34-36 oz. I recommend filling until it just barely comes out the vent then drain off a couple ounces. I honestly don’t know what mine holds but I do know it is more than 32 oz.

Thanks Cptn, I understand, you were just estimating. But assuming all of our 3.0 liter Sportmasters are the same, and if you measured two ounces drained from full, then you have 42 oz. of oil in your case, 14 oz. more than factory spec. Just wanted everyone to be aware.

Initially, I would have thought the fill to the vent was the correct way, since that's what I've been told since the 1980's. Also, I thought the top driveshaft bearing would need that oil near the top of the case, to be lubricated, since it's all the way at the top. At 28 oz, the oil would be way down from the top bearing, so I'm assuming there must be some designed in oil flow or splash that brings oil to the top bearing. Certainly Mercury would not specify an oil level that's going to run any bearings dry.

Anyway, wish you continued good luck with the way you've been doing it.

[Sleek Jr]

Put 28oz in it like the manual says. Or keep putting more in and buy the vent kit. the manual says 28oz for a reason. I filled all mine to the spec in the manual.

Thanks RR, I think I'm going to go with your advice. So many opinions and experiences here, but I tend to believe Mercury Racing, who probably has the most experience with these and has to warranty them if they fail, probably has the best advice as to oil level.

I guess the "fill until it comes out the vent" might be old school carry-over advice, without knowing current specs what the factory fill was/is on these newer drives.

Because mine WAS filled to the vent by previous owner or shop... that's what started me on this quest to know the correct fill level.

Thanks,

[Captin Hazlewood]

Sleek Your point about the upper bearing is spot on. Without enough oil in the case it will not get the lubrication it needs. I agree it is strange that you don’t fill these gear cases to the vent like every other gear case on the planet. I have been filling mine to the vent and draining off a couple ounces for the past 11 years and have not had any issues. Draining off those couple of ounces gives the room needed for expansion. I don’t have a factory manual so I can’t personally vouch for anything the Manual says but I doubt it says fill with 28 oz. I suspect that figure may be listed on a capacity chart. Perhaps someone can post a copy of the fill procedure from the Manual. Good luck with whatever you decide.

[Sleek Jr]

This site shows 858 ML for the 3.0L which converts to 29 oz.

https://www.mercurymarine.dk/_Resour..._Guide_Low.pdf

[Basnova]

Thanks RR, I think I'm going to go with your advice. So many opinions and experiences here, but I tend to believe Mercury Racing, who probably has the most experience with these and has to warranty them if they fail, probably has the best advice as to oil level.

I guess the "fill until it comes out the vent" might be old school carry-over advice, without knowing current specs what the factory fill was/is on these newer drives.

Because mine WAS filled to the vent by previous owner or shop... that's what started me on this quest to know the correct fill level.

Thanks,

I know this is an old thread, but I was curious as to how much you ended up filling and your results with seals and overall health of the internals.

[4Speed]

All I can say is my 3.0L 225 Sport XS with a Sportmaster on a STV had its first few oil changes filled to the vent plug (I did them). Then one fall I pulled the drain plug and the oil (Mercury High Performance 90W) had water in it - no metal on the magnet but it was light blue and milky. Thanks to S&F I came across MAD EFI and their seals so I did the shift shaft, drive shaft & prop shaft and read in the manual about the 28 oz so that is want I did. That was a few years ago and the oil still has no water in it when I drain it in the fall. Coincidence; who knows by where the oil remains water free and no metal on the magnet I drank the 28 oz kool-aid and so far it works.

[25two.stroke]

Kinda weird but I just started having this issue on a CLE. I know this is a big problem with the 3.0L sporties and I have run into that. I typically fill them till it just starts coming out the top and then loose a little bit. Done that one many customers' 3.0L sporties and never had an issue blowing seals.
On my CLE I would notice weeping out of the shift shaft seal a day after every time I ran it. Never got milky, just would weep out the drain hole for the shift shaft cavity a day or two after I ran hard. I replaced the seal with a new...it did it again and blew the seal out the top. I changed the whole shift shaft bushing with a new one...it blew that seal out. I glued a new seal in with loctite bearing+seal retainer and drained a couple oz of gear oil out of it...that time the seal stayed in but it seems it blew some gear oil out past the seal. Just burping up. I pulled it apart and replaced the shift shaft and the seal too in case the shift shaft had a bad spot on it. Ran it again and I still see oil weeping out of that drain hole. Never any water in the oil, its just over pressuring. Need to pull it off again to see if the seal stayed in place but I am getting fed up with it. I am running high, but not THAT high. Only like 2.375" above the pad. I've even run other CLEs on it and they all do the same thing.

[Basnova]

All I can say is my 3.0L 225 Sport XS with a Sportmaster on a STV had its first few oil changes filled to the vent plug (I did them). Then one fall I pulled the drain plug and the oil (Mercury High Performance 90W) had water in it - no metal on the magnet but it was light blue and milky. Thanks to S&F I came across MAD EFI and their seals so I did the shift shaft, drive shaft & prop shaft and read in the manual about the 28 oz so that is want I did. That was a few years ago and the oil still has no water in it when I drain it in the fall. Coincidence; who knows by where the oil remains water free and no metal on the magnet I drank the 28 oz kool-aid and so far it works.

Congratulations on resolving your issue, but did you put the seal kits in, AND lower your fill amount at the same time? No offense, but if you did, then we don't know if one or the other was the cure, you know what I mean?

I have both the owners manual and the Service Manual. The owners manual says 22.5 oz., and I can't seem to find what many on here report in what I assume is their service manuals saying 28 oz. Do you remember in what section of which manual says 28 oz.?

In any event, mine takes MUCH more than 28 oz. before it even begins to seep out. In fact, I got chastised pretty heavily on this forum when I mentioned that mine takes so much oil. I was told I must not be filling it correctly, I should take it to a pro, etc. I finally made it a point to specifically track how much it takes each time I refill and my case without a doubt takes 38 oz. before weeping.

I've spoken to some knowledgeable techs who have separately worked on my motor and lower end over the years, and although they are aware of the potential for sucking in a little water, they all tell me to fill it to the vent citing concerns of the top bearing not getting enough oil, especially given the fact that the interiors of casted cases vary in capacity. I am tired of worrying about the seeping of water coming in since I bought mine new 25 years ago, and am finally considering seal kits and overflow reservoir. In the meantime I'd like to see if filling it a little less would help. But, I recently got new gears, and had my steel shafts swapped out for stainless, and I'm not sure it would be wise of me to risk all the work that was done and run 28 oz. because that would put me so low compared to the 38 oz. capacity of my case. That's only 75% of what my case holds. Two days ago I drained and refilled with an entire 32 oz. bottle, and lost about an oz. putting the plugs in, but I'm still scared about that top bearing. Any thoughts on that?

[Basnova]

Kinda weird but I just started having this issue on a CLE. I know this is a big problem with the 3.0L sporties and I have run into that. I typically fill them till it just starts coming out the top and then loose a little bit. Done that one many customers' 3.0L sporties and never had an issue blowing seals.
On my CLE I would notice weeping out of the shift shaft seal a day after every time I ran it. Never got milky, just would weep out the drain hole for the shift shaft cavity a day or two after I ran hard. I replaced the seal with a new...it did it again and blew the seal out the top. I changed the whole shift shaft bushing with a new one...it blew that seal out. I glued a new seal in with loctite bearing+seal retainer and drained a couple oz of gear oil out of it...that time the seal stayed in but it seems it blew some gear oil out past the seal. Just burping up. I pulled it apart and replaced the shift shaft and the seal too in case the shift shaft had a bad spot on it. Ran it again and I still see oil weeping out of that drain hole. Never any water in the oil, its just over pressuring. Need to pull it off again to see if the seal stayed in place but I am getting fed up with it. I am running high, but not THAT high. Only like 2.375" above the pad. I've even run other CLEs on it and they all do the same thing.

So, what are you planning to do? Run less oil, add seal kits, add expansion kit....?

[XstreamVking]

The oil does climb the shaft when it spins as it was designed to do. This is what lubes the upper bearing as was told to me during merc school. Now, if you run the lower wt oils (redline amsoil etc) you better get the vent and expansion tank and fill it up. JM 2cts.

[Basnova]

The oil does climb the shaft when it spins as it was designed to do. This is what lubes the upper bearing as was told to me during merc school. Now, if you run the lower wt oils (redline amsoil etc) you better get the vent and expansion tank and fill it up. JM 2cts.

I think what you're saying is running a little less oil is OK, but doesn't it seem to you like 28 oz is too low in a 38 oz case? And, does the design mean if it's not full, the bearing runs dry for a bit until the oil has had time to get pushed up there? Surely, that's not good, is it? What about what I said about me filling 32 oz and 1 oz draining out as I insert the drain plug? Would that be better? I'm running the Merc Extreme Performance oil. Does that change your thoughts any?

[XstreamVking]

merc gives fill specs for a reason. They know the units are gonna be surfaced and want it to have some room for expansion. The xtream merc gear lube is thick, 85-90 wt I think. It can climb fine. Just the lighter oils have problems climbing the shaft. Heck, just feel your lower after a long hi speed run... They get quite warm in fla.

[4Speed]

I did the seals and 28 oz at the same time.
I revisited the manual I purchased when I bought the motor new and it says the following:
Option 1 - Slowly fill to the vent
Option 2 - Capacity approximately 710 ml / 24 oz
Option 3 - Mercury Racing gearcase approximately 828 ml / 28 oz

Where mine is the Sportmaster on a Mercury Racing Engine I went with Option 3.

You will also see the August 2005 date on one of the pages and I purchased the manual new in 2010 from Mercury.