Did used them on my E30 and E32 - no noticeable immediate benefit. I am giving it a benefit of doubt - hope it prolongs engine life. Personally for less than 100 RM, its ok for me.
Did used Slick 50 on my 1975 Alfa Romeo Berlina 2.0 ( clocked >300 K ) - it does reduce oil consumption and my belina still going strong !