Recently bought a boat with a 525 that has pretty dark looking oil. Are most people taking the boat in for oil changes or doing it themselves? Anything different about these engine besides extracting oil and changing filter that needs to be done? How many quarts do these 502's hold? How often are most of you doing changes? Thanks for your help!

Newbie

DIY and they take 8 qts of oil. Mobil 1 15-50 is what I run. You should have an oil drain line off the oil pan to run out the transom drain plug and drain directly into an oil catch pan. I change mine every season 20-25 hours.

I imagine that the oil filter should be changed everytime that a oil change is done? I know there was a thread about this, but does anyone have a recomendation of what type of filter should be used...or maybe more importantly, which filter shouldn't be used?

Here is a good thread on oil filters. I use the Purolator Pure One filter and it is a high quality filter.

http://www.offshoreonly.com/forums/s...ht=oil+filters

NEW: (2) Merc 525 race oil filters for sale...20. includes ship. e/m at my screen name @msn.com or call Dave 414-254-0733 thanks

sold!! to local OSO brother

I was too late!! Damn!!!

20 to 25 hrs on that motor. It's ok to use Mobil 1 synthetic. It will burn some, so keep up with it every time you use and/or over long cruises. Keep an extra filter with you along with about 4 quarts for just in case.

PS: change your outdrive fluid at 50 hrs as well.

I have a 502 and I run 15w40 mobil 1300 super diesel engine oil this oil meets all the gas specs. or you can run rotilla oil for as the filters run napa gold or napa racing filter or wixs racing filters these diesel oils still have zinc and or metals that the engine needs to live on. alot of the new gas oils have been taken to a very low limit on the metals to meet emission requirments

http://www.mobil.com/USA-English/Lub...1300_Super.asp

Recommended for use in high performance gasoline engines and mixed fleet operations.
Diesel-powered equipment

fram filters SUCK !!!!!