If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterThermostat Installation
Replace the O-rings [A] with new ones, and apply grease
to them.
Assemble:
O-rings
Thermostat Housing [B]
Thermostat [C]
Thermostat Cap [D]
Install the thermostat [A] in the housing so that the air
bleeder hole [B] is on top.
Tighten:
Torque - Thermostat Cap Bolts: 5.9 N ...
Liquid Gasket, Non-permanent Locking Agent
For applications that require Liquid Gasket or a
Non-permanent Locking Agent, clean the surfaces so
that no oil residue remains before applying liquid gasket or
non-permanent locking agent. Do not apply them excessively.
Excessive application can clog oil passages and
cause serious damage.
...
Storage
Preparation for Storage
Clean the entire vehicle thoroughly
Run the engine for about five minutes to warm the oil, shut it off, and
drain the
engine oil.
WARNINGEngine oil is a toxic substance. Dispose
of used oil properly. Contact
your local authorities for approved disp ...