Increasing oil level on Nissan 9.8 hp

[BobGlover]

I've got a 3 yr old Nissan 9.8 hp that's on our pontoon boat (9.9 hp limit on lake). I changed the oil about a year ago but didn't check it last year. When I did check it recently, before running it for the season, the dipstick showed over full. Also, the motor was really running rough. I flushed out the carb. with solvent and changed the oil, adding about 600 ml and the oil level now shows about halfway on the dipstick, where it should be. The motor runs fine now. My questions are : 1) what would cause the oil level to increase, and 2) would draining the excess oil have any effect on the smooth running? Before I did the work, it started and idled fine, but would cut out at high speeds.

Thanks a lot. Bob

 

[pvanv]

Re: Increasing oil level on Nissan 9.8 hp

All 4-stroke OB's, of all brands, tend to "make oil". The problem is exacerbated by slow running and cold water. The issue is much worse with synthetic oil. Run only non-synthetic 10w-30 oil that is rated FC-W. There is an FAQ on this board that details it very well. Your oil should be changed every 50 hours. If necessary, you can lower the oil level, but considering that you only use about 3/4 of a quart for a change, it's better to just change it and get rid of the diluted oil.