Would I need to use ring free or carbon guard if using xd 100 oil

[tacklejunkie]

On a 150 hp Etech?

[boatfixer]

Under relativley normal conditions I'd say not likely. The direct injection motors are certainly much more efficient, as long as you use the correct oil. But it would also depends on how you use it. For instance, if you trolled constantly with it, that would increase the chances of carbon build up. Then consider the quality of the gas. Poor grade, old etc and you may not have a good clean burn. Using those type of additives will certainly won't hurt and if nothing else, give you peace of mind