I'm going to leave it for now and do some more research, don't want to rush it just to regret it and cry after I crack the upper oil pan, saw that it happens quite often. I learn something new about it everyday, the weather now isn't so great anyway so I'll wait it out so I don't have to roll around in the mud under the car I contacted the seller on eBay and they'll send me a new adapter, the sensor and gauge is some cheap set for like £15 so nothing too crazy, but could argue that it's not some advanced tech to justify sets going for like 10x more. Someone on Reddit just informed me that the OEM switch seen on the photo by the oil filter isn't needed and can just be unplugged, so I'm thinking about buying an adapter without a tee like this:
Would make things simpler although the OE switch could function as a fail-safe (switches if it goes below 8psi?) in case the extra sensor fails. I decided to go with a sealant paste instead of the teflon tape too to avoid excessive pressure in the thread inside the aluminium pan. This feels way more complex than one would think, there are tons of posts on the Internet about cracking the pan while screwing the sender in, makes me think if I should really do this myself Damned if I do, damned if I don't, without the sensor I'll wonder if I'm killing the engine unknowingly every time I drive it, I can't believe Nissan decided to ditch the pressure gauge for a clock. In the end I might get someone to do it for me although I enjoy doing things myself, I'd rather be safe than sorry. Paying 1/2 hours of labour is cheaper than the upper oil pan swap