Anyone fitted an oil valve to their sump?

Easier to buy a vacuum oil extractor if you want quick and clean oil changes.

How often do you change you oil?

Interesting and looks good in principle but...
It replaces the sump plug so if you're motor has low ground clearance (it can happen - even on this forum ) you risk ripping it out on a speedbump
If you are thinking about it 'cause you have a stripped plughole in the sump, it won't help

As a gimmick for an off-roader - possibly - but be prepared for it to seize up if it gets covered in muck.

Don't forget, "Just because" is always a good reason to do it anyway

Obviously. Because when I was a wee nipper up to no good I was always crawling under cars to see if they had had the sump plug replaced with a valve so I could drain their sumps. Oh the high Jynx.

Serious time, I'll second the vote to vacuum discharge if you need to do a lot of oil changes regularly.

Drilling tanks is fuel theft. No one is stealing used engine oil. I hope

I doubt it. Seeing as garages are still paying to have it removed why would you nick it? Just ask garages to take it from their hands
If you want to go down that route, weird tampering, randomly draining the oil JUST because it has a valve fitted to the sump would be about as odd as finding a trailer hitched to my landrover overnight just because it has a tow hitch or something. Overthinking on your part perhaps. I see the concern but I don't believe it's real.