I have changed my oil a few times and usually fill to top install plug unscrew pump and replace drain plug. I have read on here to let 2 oz drain before installing drain plug. My owners manual does not say that, is states fill to top and replace drain plug as fast as poss. I was taught that air in a non-vented system will compress and build pressure if left in. That is why to fill void completely. Just wondering.
THX
2022 Caymas cx20pro 250 Pro XS s/n 3B099812
Air will compress.... whereas the fluid will NOT (at least not as readily), resulting in elevated gearcase pressures when the case is run at elevated mounting heights.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 48 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Reply With Quote
