"Scudo" was pretty close when he stated;

In 4 stroke engines the heat generated causes a breakdown of the chemical
composition and makes the oil more chemically acidic when compared to
fresh
oil,
Not entirely true- it's the impurities and contaminates (due to incomplete
combustion) that cause the acidic buildup. Heat causes the lubrication
properties of the oil to breakdown which gradually increases wear in the
motor (but does NOT add impurities).


this oil if left for a period of time can have a corrosive effect on
the metal parts of an engine.
Agreed.


This is the main reason why any vehicle that
has seasonal usage only should have an oil change before it is stored and
not left in the vehicle over a long period with the old oil and then
changed
at the start of the season.
Agreed.


With that in mind and the fact I only use the (2 stroke) lawn mower for 4
months of the year, I was reckoning that to a lesser degree the above may
apply.
How can it apply to oil that has NOT been exposed to combustion? If the
two-stroke oil had been exposed to combustion, it would have come out the
exhaust and you'd not have a problem!

There are other problems that should be addressed before that- such as the
tendency of gasoline to become 'gummy' after sitting for a period of time,
proper corrosion prevention, etc.


I have no wish to continue with this thread
So.

so any replies will be
unanswered.
Like you were providing good answers previously?

^^