This is true. It is "risky". This is why I said earlier that it's never my FIRST effort.... it's usually (for me) kind of a "last ditch" effort.
However, in spite of the risks, I'd do this LONG before I'd use Wynn, or STP, or any of those other "oil additives". Frankly, I'd remove and tear-down a motor long before I'd use those other additives. (there's another recent thread about this)

FWIW: at various times over the years, I've used MMO, ATF and straight Diesel fuel, each with success. But not ALWAYS with success. And yes, ALWAYS follow-up with an oil change. You are not just changing the lubrication properties when you add this, you're also TRYING to break-up deposits in the oilways... so if you're successful, you want to get those OUT of the crankcase... not let them circulate around through the motor some more.

Ok so a 50/50 mix of Mobil 20W50 and 0W40 just makes the noise louder (yes the Mobil tech guy didn't see an issue with this....I've done it with air cooleds before). I've thus resigned myself to changing the offending lifter/s. After having a look at access for an "engine in" job I thought an engine drop might just be easier until I watched a 3 part series Youtube video of the whole procedure :) There is a lot too it. I'll spend a couple of hours and see how it goes.

So.... ymmv.... but I've been known to put a quart of diesel fuel in the crank case, get the motor hot, let it cool, repeat 4 or 5 times, then drain and flush. Oil change again in 250 miles.
This has saved many hydraulic lifters for me over the years.

Ymmv.

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Tick went away shortly after doing the oil change a month ago. Was it the dose of MMO, an oil change (not that it was due) or did it just clear up on its own? Who knows?

As posted earlier, I’ve used a quart of MMO for years now just before the oil change. I drain a quart and replace it with a quart of MMO, Drive for 500 miles and change the oil. I change oil every 3000 miles. Just got my latest Blackstone analysis and it said, “Your Boxster is producing some great wear trends. Once iron settled down after the early analysis, metals have been low and quite consistent, and that’s a healthy trend. Silicon is staying low for the fourth repot in a row. The thin viscosity persists, but given these great wear trends, the engine certainly isn’t bothered by it. No water, coolant or fuel present. And insolvables at 0.1 show oil filtration is working well.”

Viscosity is at 64.2 vs range of 65 - 78. All I know is that my lifter tick went away and never returned using this process and that was years ago. Is it the MMO? My vote is the frequent oil changes but I give a definite nod to MMO.