[Megalocnus]

It is called Liqui Moly Pro-Line engine flush.

I guess it does help, but don't expect miracles, especially if your engine has been burning a lot of oil for a long time. It is safe, cheap, and easy enough to do, so there are no downsides in adding two 500 ml cans to the crankcase just before oil change.

I have tried both Liqui Moly and BG EPR engine flush products without any improvement, probably because I didn't catch the issue early enough. But do search for a post by MrMcar, where he describes how he managed to clean the oil control rings of an oil guzzling engine with Liqui Moly engine flush, letting it idle for eight hours - way longer than the recommended 15 min.

 

[Megalocnus]

This is a very good oil for the price, but also don't expect much of a difference.

I thought for a car still burning less than a quart of oil per 1K miles, the engine flush before oil change may be worth it, not so much once it gets to burn faster than this.

 

[Megalocnus]

I don't think that will work. The cleaner works suspended in oil, getting hot and actively cleaning.

+1. This type of soaking, regardless of the solvent applied, would mostly work for carbon on top of the pistons, wouldn't do much for deposits on the oil control rings.