Loren

Sorry, no such thing as a "sealed battery".
Optima and batteries like Optima always include a safety pressure relief valve. This valve will activate when the battery is recharged at high voltage, typically greater than 2.30 volts per cell. So the key to the "Optima type" batteries is to not overcharge and make sure the car's charging system is working properly at the proper charging voltage.

Steve's MLC

I'm about to buy a new battery. Even though Optima is not sealed as you say does it have an advantage over other batteries with that set up? (Not needing the vent)

Loren

My point was that "all" batteries have some sort of venting - whether natural or as a safety feature.
I personally do not see any advantage in "street" batteries available - they are all about the same as far as performance, durability, and weight.

IMHO you want a battery with a vent in these cars. Remember your battery is a few inches away from your fresh air inlet (pollen filter) so any outgassing could be pulled right into the cars cockpit. Not to mention the damage acid fumes can do to paint and electronics.

theporscheguy

I would agree with the venting requirements. A friend had a battery installed and the installer did not connect the venting line. The battery was close to the ECU (some domestic brand...) and the gases caused the ECU to then have problems. Not good.

white out

Based on your picture, your negative battery terminal looks loose.