OK so no one here seems to have any first hand experience with it.
But guys keep an open mind. I'm not writing this out of the blue with no prior experience with the mainstream additives you guys use.
Prior to this I did a full 2 cycle apply, flush, re-apply and flush again with Auto-RX.
Following that I've been using LC-20 and FP-60 for a couple of years.
These seem to have quite a following here.
This is my SUBJECTIVE observation to date so please don't split hairs with me over what follows.
Auto-RX, great product seems to do a good job cleaning engine. No noticeable effect on friction reduction but did seem to thicken oil a little so engine ran a bit quieter.
LC-20, On initial application seems to smoothen engine a bit but not that much. Within a couple of hundred miles friction reduction effect gone and by 1000 miles later it seems to have made oil worse, ie. engine running noisier and sluggish, possibly friction gone up.
LC-60, great stuff would recommend it.
I've been using Schaffers 10-30 in a Mercedes Benz W-124.
Observations of Ionlube so far, ie. about 300 miles.
Applied it after last oil change, my oil change interval is about 6000 miles. Last oil used was Schaffers with LC-20 used as follows. 2 oz per quart at oil change and 3 oz every 2000 miles. The guy who sold it to me said this was a new dose recommendation from manufacturer. True or not I don't know. Performance with the Schaffers/LC combo nothing special. My fuel efficiency with this batch of oil/LC-20 combo is about 3 to 5% below what I used to get. Just before oil change the engine was beginning to idle rough, and was a bit noisy, could hear it laboring when accelerating hard and wasn't quite so responsive.
After oil change, used same oil...Schaffers 10W 30 again and like new oil change things slicked up a bit. I didn't make any engine adjustments so CO, idle and timing left as is. Drove for a while to get a feel for the new oil.
Then added Ionlube:
On initial application seemed to smooth and quieten engine even over the new oil...good. While driving the next 30 miles it seemed to smoothen and quieten the engine further reaching a peak around 30 to 50 miles after application.
Now engine is idling smoother and is about 150 RPM faster than before, might tune it down a bit but will wait to see what the fuel efficiency is before I do so. On second tank of gas after application and gotta say the engine is really really smooth. Accelerates at the lightest touch and is extremely smooth, powerful and quiet in top gear. And engine is so responsive in top gear that it feels like I could do with an extra gear. My car is a 4 speed auto and an extra gear would be just about right.
At this point in time I'm a real happy camper. Its doing everything it says but I wouldn't go to the extreme of running the car with no oil or anything. I'm going to push oil change to 18 or 20K miles before doing a UOA. This should be enough to show if its done its job. I know what the car feels like when the oil is at the end of the road and if that comes before the 20K I'll change it out.
Right now its too early to tell if the friction reduction is temporary like LC-20 or as long lasting as they claim. Will keep this forum posted.