'99 Optimax 225 - excessive oil use

[ackman]

This OB was "new" to me @270 hrs. It's an easy starting motor, idles fine, operates OK through all RPM ranges. I noticed a good 3/16" layer of tarry gook inside the prop snout and didn't think much about it until I noticed how much oil this OB uses, about 1.75+ QT every 2 hrs. I replaced the plugs, finding the factory originals still installed, which looked OK though. No Merc dealer has heard of an excessive oil use problem, and Merc tech support confirms that this serial range OB had no "issues" or recalls. They suggested replacing the ECU though. Anyone run into a similar problem?

 

[Dr1532]

Re: '99 Optimax 225 - excessive oil use

my port motor uses more oil than the starboard,have issues with it not sure if i have fuel /air problems or a oil problem gettin the plugs dirty.let me know how you make out

 

[ackman]

Re: '99 Optimax 225 - excessive oil use

A Merc dealer spoke to the engineer who worked on the early Opti's. He stated at low revs/idle oil use was less than 100:1, 25:1 in the 3800-4300 RPM range, and better than 50:1 as the revs increased from there. Even so, my oil use comps give me 1.15 qts.used for every hour of run time. An average harbor trip for me is 30 minutes at idle, 40 minutes in the sweet spot of 4200, the balance between 4800-5200. Go figure