Hi!
14% oil will be just fine!!
The recommendations is just that : A recommendation...and as such does only show a persons thoughts or at best, a companies thoughts of what works.
Always remember this is not rocket science...there is a rather wide margin within how engines work and the border line is not whether to run 14% or 18% oil. In a car engine there is definitely other things to worry about than 14% or 18% oil...and that is avoiding the engine inhaling dirt of any kind and not setting the carb lean.

Regards!
Jan K
Sweden