SCP Foundation

^{note that this isn't every single mistake, just some stuff that stuck out to me}

site-██

Capitalize "Site."

5x6x5 meter room

Very specific measurements, but nothing about the actual room — I'd remove the measurements unless they really matter and then specify what kind of containment area it needs (just "standard ___" works here).

Nine-Tailed Fox (E-11) is designated instant access to SCP-3425's container and SCP-3425-1 in case of a containment breach of SCP-3425-3.

Firstly, it's "MTF Epsilon-11 ("Nine-Tailed Fox")." Secondly, Epsilon-11 already have instant access to any SCP containment in the case of a breach, I'm pretty sure — this comes off as an attempt to add extra importance to this thing, and as a hamfisted crosslink to a very popular MTF.

Description:

Start text immediately after this, rather than leaving a line in between.

SCP-3425 is a 1 meter tall rusted zipper on the side of a concrete wall inside what used to be conference room-██.

Tone is very shaky here, and the sentence is hard to follow.

SCP-3425 cannot be zipped open even with extreme force unless SCP-3425-2 oil is poured onto SCP-3425, once about 350ml is poured onto SCP-3425, SCP-3425 can be unzipped.

Again, hard to follow, and this time it's a run-on sentence as well. Also, I don't even know what SCP-3425-2 is at this point — it makes no sense to mention it.

SCP-3425-1 is a bright, surreal world where gravity changes in certain places, time flows incorrectly and all is inverted.

"Bright, surreal" is a not very scientific way to describe the dimension. "Surreal," especially, makes no sense in the context of a scientific document.

This is the home of SCP-3425-3.

I'd remove this sentence entirely. It tells us nothing about the dimension, and we don't even know anything about -3 yet. You can just say -3 lives in -1 when you talk about it.

This is where I'm going to stop doing a detailed line by line. As you might have noticed, nearly every sentence you have is problematic. Below, I will just note some examples of egregious tone:

an unknown oil-like substance that can 'oil' anything with ease. E.g. Oiling a bicycle chain.

black urine which is nothing to worry about.

SCP-3425-2 oil can has been known to

Subjects have reported strange noises

(Don't call someone a "subject" unless you've established the experimental procedure they're subjected to. That's what the term "subject" implies.)

what he and his friend did during the discovery of SCP-3425 in conference room-██.

And there's:

Dr. █████: After yesterdays incident, would you like a photograph of the black creature?

Dr. Udwane: After what that [EXPLETIVE] thing did to ███, hell no.

This sounds directly ripped from 096, but doesn't even make sense in this context.

Portals to other worlds are always interesting, and making the portal accessible by a giant zipper is certainly original enough. This had my attention, but ultimately just makes too many mistakes for me to like it beyond the idea.

I suppose I'll start with how this thing was discovered. The doctors who first stumbled upon this thing are so damn incompetent. You'd think that a couple of Foundation researchers would know better than to go fumbling around with an undocumented anomaly without reporting it first, right? Exploration isn't their job, and what happened to the other stupid doctor is exactly why.

The world itself is pretty dry and uninteresting. It's just a weird-looking place with a 'thing-that-kills-you' living inside of it. There's no story here, nothing to really creep me out or make me care about anything that I'm reading.

The audio logs are just dumb and random. They add absolutely nothing to the anomaly itself, and there's no context as to why they're there. The exploration logs are equally sloppy. None of the D-Class that go in nor the doctors that are supervising them read like real people, and I don't buy that the Foundation would promote a D-Class to a full Foundation employ for running in fear from a twitching black monster.

-1, unfortunately. Good start, pretty bad everything else.