What position do you stow it in?
I have an
outboard in a well. I also have a Tohatsu 6hp 4-stroke.
I do not care much for this
motor, IIRC I bought it in 2010, but it might also be a 2009 model... the
motor was not changed since 2006 IIRC.
The Tohatsu,
Mercury, and
Nissan are all three the exact same motor.. all are produced on the Tohatsu factory line with the difference being the decals.
Storing it on the correct side (as per the manual and the decal) will still allow a small quantity of
oil to leak into the cylinder. It smokes when first started, but I have noticed it only does this when I have removed it from the well and laid it down.
I am on my third
oil change (I changed it at 10 hours as per the manual and then did a second 10 hour
oil change because I am somewhat anal about maintenance).
I use Tohatsu branded oil.. which is not synthetic.
I have 2 ideas as to your problem... one is the oil leaking past the rings when stowed but that only applies if you stow it on it's side (or raise it on a transom mount?)
The other possibility would depend on the oil you use. Synthetic oil is great stuff, but should not be used for the first several oil changes. It may not allow proper seating of the rings which can cause oil burning. I have seen this, and it is in user
manuals on many small motors (can not
recall if it is in this one.