Re: Power tilt and trim
In principle you do not have to change that oil.You use that oil very little and it has no reason to go "flat"
You must however check the oil level regularly and if you see that some went missing, you must check for signs of water in the oil.If you find any,(whitish milky color) you must check all the seals and make sure everything is hermetically closed.Then you replace all the oil.
If you see a little missing after a long period of time,just add some.You can use automatic transmission oil.