Chevrolet 2007 Corvette Owner's Manual page 335

The engine oil level must be checked when the
engine is warm. Cold oil level in the dry sump tank
may not indicate the actual amount of oil in the
system. With this system, engine oil is contained
in an external tank, separate from the engine.
Under normal operating conditions, the oil
pan under the engine does not store any oil.
If the vehicle has been parked for an extended
period without the engine being started, some
oil will seep back into the oil pan, reducing
the amount of oil held in the dry sump tank
and there could be no engine oil at all showing
on the dipstick. This is normal since the
dipstick is designed to read engine oil level
only after the engine has run long enough
to reach normal operating temperature.
Do not add engine oil based on cold engine
dipstick readings. The engine oil level on the
dipstick will also be inaccurate if checked while
the engine is running.
1. To obtain an accurate engine oil level reading,
warm up the engine to at least 175°F (80°C).
Cold oil will not give a correct oil level reading.
2. Once the engine is warm, turn off the engine.
Checking the oil while the engine is running
will result in an incorrect oil level reading.
3. Wait at least five minutes (but not more
than 20 minutes) to allow oil to drain and
settle in the engine.
4. Remove the dipstick from the external engine
oil tank and clean it with a lint-free paper
towel or a cloth. Re-insert the dipstick into
the external oil tank, pushing it all the way
in until it stops.
5. Remove the dipstick from the oil tank and
read the level on the cross-hatched area.
Oil levels that fall in the cross-hatched
area are normal.
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