Reducing Outboard Engine Smoke
If you happen to own an outboard motor that suffers from excessive engine smoke, switching to a synthetic oil can help to make a significant reduction in the appearance and production of smoke. Synthetic oils like the evinrude XD100, and the evinrude XD50 oil run cleaner than mineral oil. XD100 oil is a full synthetic that will cause the most dramatic reduction in smoke, however the downfall is that it is more expensive. XD50 is a hybrid synthetic that combines mineral and synthetic oil, it costs less than XD100, and will still help to reduce smoke.
Once you’ve switched to a synthetic oil be mindful that you cannot switch back to a mineral oil. Synthetics seal the engine with their own particles, and should those particles dry out, the engine can crack.