# Lower Unit Oil Milky?



## T Bone

In doing my annual maintenance over the weekend, i noticed my lower unit oil looked different then what i was accustom to. Motor is a 2007 Yamaha 25hp two-stroke





















This is the first year i have changed my lower unit oil after using Yamalube Marine Gearcase Lube, which looks like this fresh







I've previously always used West Marine Hypold 90 Lower Unit oil which is more a dark blue/green color.

My question is, should i be concerned about my lower unit oil color? I originally thought that it may be milky due to water intrusion from a seal issue. But then i got to thinking that maybe the used yamalube with a little left over west marine oil made it that color and in fact its not milky?

Sorry, i may be over thinking this. Just want to see if i should be concerned or not?

Thanks guys


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## yobata

I change my seals every time I change the lower unit oil. They're really inexpensive at less than $5 for both and worth it in my opinion. Sorry I don't have an answer for you as far as the look of that lube - I use Mercury/QuickSilver lower unit oil and its dark green/blue (also have a 2 stroke 25hp Yamaha - 2006)


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## Guest

Do as @yobata said and change the seals when changing lube. That oil doesn’t look bad from the pics though. I would run it a few trips and change it again to check it.


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## Hardluk81

Any of you know of a magical tool to pull the prop shaft seals? I’ve been searching with no good results. Best thing I’ve found is a DIY. Bevel the end of a piece of metal threaded pipe that will fit over the shaft. Slide it over the shaft and screw it in between seal and shaft. After that should be able to pull seal out with said pipe. I haven’t tried this because I don’t want to scar my prop shaft causing bigger issues. Sorry for the hijack.


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## Guest

If doing seals I always pull the prop shaft housing and replace the large o rings that are on it at the same time. Makes removing the shaft seals pretty simple


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## not2shabby

You change those oil seals and o-ring every year with a gear oil change? I guess that makes sense, but I feel like every seal change risks scarring the bearing housing.

What about the upper oil seal on the drive shaft? 

I'm about to jump into a minor re-build because @sjrobin pointed out on Saturday that my prop shaft is bent. I need to replace the shaft, so I'll do new seals, o-rings, and ring nut. Curious if I should also install a new needle bearing.


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## Snookicide

That milky color and consistency is most likely due to water intrusion. It will not break down from use and get lighter, like other oils as it breaks down and gets used it darkens. Time to change seals and when you do your water pump do the whole kit and not just the impeller. I have serviced my families Yamahas for over 20 years with Yamaha products and saved lots of money over the years, but never skimped on the maintenance. My current Mercury on the other hand will mostly be done by a shop because, well let’s just say that did not go as smooth. Personally for me, water intrusion would be time for a mechanic to look at it, because if you miss something you can risk requiring a whole new lower unit and a tow home from part failure.


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## topnative2

OK....A lower unit will sometimes have condensation in the lower unit so before you change it you need to to put the thing in gear and let the oil mix itself up.....a lot of times the milky will disappear which means no water problem.Now if you really have a milky green issue it will be instantly obvious.Changing seals on every lower unit oil change is a waste of money if your oil is "clean". A pressure test will be the definitive answer if yours are shot.
Fishing line is the biggest problem followed by bent prop shaft and, finally, age from sitting and no use.


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