Hello, my brother has a 25 hp yamha that he say,s when he went to put oil the lower unit the oil ran out the water intake. Is there a seal out somewhere?

the oil in the lower gear case in a outboard motor should be changed every fall when you take the boat out or once a year if you live where you can boat all year. when you look at the lower unit down by the propeller you will find two screws one lower and one upper. take the upper one out first and check the nylon gasket and replace if worn. put a coffee can or and oil collector under the moter and take out the lower plug. if possible do this after the moter has been run recently, but never run an outboard out of the water unless you have the garden house hooked up to ear muffs over the water intake sites!
the oil will slowly drain out. if the oil looks like chocolate milk it probably has water in it which means its leaking at the upper or lower seals and needs a pressure check and possibly seal replacemant. after all the oil is out (30 minutes or so) its time to refill it. for less than ten bucks you can but a simple device that lets you pump the oil in instead of squezzing it out of the tube. you attach it to the lower drain plug hole and the to a quart of the proper fluid for your motor. make sure you buy the oil to match your type of outboard.
pump the oil or squeze it it from the bottom until it starts to come out the top hole. make sure all the bubbles are out then put the upper plug back in with good gasket, remove the oil tube or appicator from the bottom hole and quickly relace the bottom plug as well with a good gasket.
thats it and you are good to go for the season. if you see oil leaking out the prop shaft or at one of the plugs you need to attend to that soon. tip remember chocolate milk oil or actual water means a seal leak and must be repaired.it may just be a .25 nylon seal for one of the plugs is bad! any unusual noises of difficult or loud shifting can also means problems with the lower unit gears etc and its always cheaper to fix the problem sooner than later.
happy boating!!!!!!!!!!!!