I always prefer a drain valve over a drain plug and install one on all my cars.
A valve makes oil changes faster. It eliminates any splatter while draining. And it makes it easy to take samples for oil analysis or to drain excess oil added for track use if you aren't going to change oil right after.
Most of my cars have Fumoto valves which are a ball valve with a lockable lever. But the lever body won't clear the ATS oil pan while the valve is being installed. You can get an extension pipe to mount the valve outboard, but I don't like that idea for several reasons.
I searched for an alternative and only came up with one viable one for the ATS. There were several aircraft drain valves that could be fitted but some were very expensive (over $100) and most had no way of locking the valve since they normally are inside cowling where the lever could not get bumped in flight. I found a European brand for road vehicles, but they don't make one with the Cadillac's threads.
I ended up with a "No Spill" brand valve. They aren't sold in stores B&M or on-line as they are targeted for fleet operators looking to save labor time. But the manufacturer will sell directly to individuals.
The valve body replaces the drain plug and is cylindrical. They make short bodies for vertical drains with limited ground clearance, "regular" size where clearance isn't an issue such as the ATS where the drain is horizontal. And they have a quick change version that operates similarly to an air line coupling or garden hose quick connect. For the first two types, there is a poppet valve parallel with and in the middle of the direction of flow. The valve is opened by a device on the end of a drain hose. As this device is screwed onto the valve body it pushes the poppet valve open to allow the oil to flow into the hose. In operation, a brass cap with internal o ring is hand tightened on the valve. That prevents dirt getting into the valve body and acts as a fail-safe should the poppet valve leak. It's a very good system and a beautifully built item but is more expensive than the Fumotos for the FIRST car you do since the device to open the valve runs $13. But that device will work with all your vehicles (other than the quick change models).
Fram sold a poorly made and executed but vaguely similar product years ago. I still have one on one or two of my vehicles.
A valve makes oil changes faster. It eliminates any splatter while draining. And it makes it easy to take samples for oil analysis or to drain excess oil added for track use if you aren't going to change oil right after.
Most of my cars have Fumoto valves which are a ball valve with a lockable lever. But the lever body won't clear the ATS oil pan while the valve is being installed. You can get an extension pipe to mount the valve outboard, but I don't like that idea for several reasons.
I searched for an alternative and only came up with one viable one for the ATS. There were several aircraft drain valves that could be fitted but some were very expensive (over $100) and most had no way of locking the valve since they normally are inside cowling where the lever could not get bumped in flight. I found a European brand for road vehicles, but they don't make one with the Cadillac's threads.
I ended up with a "No Spill" brand valve. They aren't sold in stores B&M or on-line as they are targeted for fleet operators looking to save labor time. But the manufacturer will sell directly to individuals.
The valve body replaces the drain plug and is cylindrical. They make short bodies for vertical drains with limited ground clearance, "regular" size where clearance isn't an issue such as the ATS where the drain is horizontal. And they have a quick change version that operates similarly to an air line coupling or garden hose quick connect. For the first two types, there is a poppet valve parallel with and in the middle of the direction of flow. The valve is opened by a device on the end of a drain hose. As this device is screwed onto the valve body it pushes the poppet valve open to allow the oil to flow into the hose. In operation, a brass cap with internal o ring is hand tightened on the valve. That prevents dirt getting into the valve body and acts as a fail-safe should the poppet valve leak. It's a very good system and a beautifully built item but is more expensive than the Fumotos for the FIRST car you do since the device to open the valve runs $13. But that device will work with all your vehicles (other than the quick change models).
Fram sold a poorly made and executed but vaguely similar product years ago. I still have one on one or two of my vehicles.