Sounds like you may have a leak in either your tilt and trim cylinders. You can usually see oil on the cylinder below the post as a pretty good tell-tale. There is an fluid fill for the reservoirs and not much problem to fill. I've used an old-fashioned type oiler filled with transmission fluid in the past.
You may also check for a sheen of oil in the water also. If there's a leak it will make a nice sheen on the surface around the engine.
The seals in the cylinders are the most probable cause and can be a DIY project if so inclined.
