Why Metal would need oxygen

[VanishingPoint]

TL;DR at the bottom if text blocks deprive you of oxygen.

One complaint I've seen made a number of times relates to Metal Sonic's susceptibility to a lack of air, especially when it comes to its representation in SRB2. I do not have a stand on whether this fact betters or worsens gameplay, and am rather approaching this with an eye towards realism in the hopes that my explanation will at least somewhat defer people from making the claim that it does not make sense in general.

One of Metal Sonic's defining visual characteristics is the large jet engine near his center of mass. If you've ever played Kerbal Space Program (or studied aerodynamics in general), you probably know where I'm going with this; In order for jet engines to function, they need two commodities: fuel to burn and oxygen to maintain a flame. While fuel is stored directly on the craft, however, oxygen needs to come in constant supply from an atmosphere. This is achieved using an intake- the large fan-like apparatus at the front of a jet engine that pulls in air as the craft moves forward and combines it with fuel as it is burnt to create thrust. For Metal, although it's anyone's guess as to where the fuel is stored, bright yellow coloration makes the intake hard to miss (even though, thanks to stylistic choice, the fanblades have become a solid disc). Considering how Metal seems to use his jet whenever he's moving, I'd be willing to bet he needs it just to get off the ground, let alone function; As such, if there really is a less than optimal amount of oxygen being obtained from the environment, whether that be underwater or in the vacuum of space, he'd have little to no choice but to terminate the mission, which in this case means self-destruction.

I'd also like to mention one other thing that could be explained with this logic, as well as something that could be a bit contradictory to my hypothesis: First, the Metal Sonic could have been the first to use a jet engine because it was the only one that was 100% gauranteed to stay in low atmosphere for the duration of its mission; Mecha Sonic Mk. I (Sonic 2's robot Sonic) resided in space, and Mecha Sonic Mk. II (Sonic 3 and Knuckles' robot Sonic) needed to operate at an elevation above the clouds, which would not provide nearly enough oxygen to facilitate the high-speed chase on Stardust Speedway that Metal Sonic is known for.

Now for the contradiction: Boost Mode. In order for a jet engine to work at max efficiency, the intake needs to face forward. While Sonic CD's Metal Sonic makes sure to keep himself in an upright position as much as possible, SRB2's Metal almost seems to benefit from entering a belly-flop state when charging at max speed. Sonic Team Jr., please fix.

TL;DR: Metal needs his jet engine and jet engines need oxygen; Therefore, Metal needs oxygen. Sonic CD concurs, Boost Mode dissents; kliksphilip joke.
If you can think of any arguments against (or for!) my explanation (other than "but it's fiction? lol", not because you're wrong- you're not- but because I would like to avoid dead ends), feel free.

 

[Modern.Sonic-(TrueBlue)]

I like this, it makes alot of sense.

 

[time gear]

I'd argue that Metal doesn't need his jet engine, he just uses it to fly and go fast. His legs are entirely capable of holding up his weight and even walking, although I don't think Metal has ever been depicted in any official media as using his legs to run. Without his jet engine he'd simply lose a chunk of his mobility, but he wouldn't be rendered completely immobile.

However, there is another bigger problem that Metal would have to face: temperature and a lack of air pressure. In a vacuum whatever gasses might exist inside of Metal are going to be trying to escape and expand outwards, which could cause damage to his internal structure and even create gas leaks that puncture holes in his outer shell. Additionally, every single little movement he makes in addition to the use of his engine and power core will contribute to his entire frame rising in temperature with nothing to transfer the excess heat to. Eventually whatever he's using for jet fuel might even just simply explode from the high temperature, doing critical damage to his internals if not outright blasting him apart entirely. Even before that happens, the high temperatures might fry his circuitry. I'd guess this is what we are seeing in-game when Metal is "drowning" in a vacuum.

Of course, all of these are fixable issues and I'd expect that in the official continuity Eggman probably had Metal upgraded to the point he could even survive prolonged exposure to outer space by the events of Sonic Heroes. If we assume that SRB and SRB2 are meant to take place in a fan version of Sonic's history somewhere between Sonic 3 and Sonic Adventure, it's possible that Eggman still has yet to iron out these quirks in the design due to not having yet expected Metal to need such upgrades yet, and it could even be Metal's failure on the Egg Rock that would go on to inspire him to perform these upgrades in this version of history.

As for what is happening underwater, this is pretty straightforward as well; he's a robot. Everyone knows what happens when you put a running toaster into a bathtub; the results are catastrophic. If we assume that Eggman has yet to make Metal completely airtight, and more importantly watertight, it's not hard to imagine water slowly flowing into Metal's circuitry and beginning the process of frying him from the inside. Effectively, being deprived of oxygen would be the least of Metal's worries in such a situation.

 

[Player:Fusion!]

I only have one thing to say:
You're a mech enthusiast?