here is my opinion and i will give it too you straight and i don’t care what people say.
I use it! and here is how i think it works and i know it works beacuse i have seen positive results on my own cars! Lucas is in composition similar too a surup very thick very very clingy, buy itself, does it belong in a engine, most certainly not! but when used as directed in the correct engine with the correct oils, it works great. you see when used in the correct ratio it allows the oil too cling too the parts very well, and makes the oil even slicker, i mean run your engine too operational temperature, with regular motor oil i find at warm temperatures the oil is very runny and sometimes when i rub my fingers together my fingers eventually feel very grippy… with lucas it still flows very well, but it doesn’t get so runny when warm, and is nice and slippery between my fingers, has a nice film… its great for older engines with 5W-30 10W-30 oils or what not, the 3800 V6 in my car loves it!
when i use it in my engines i notice a difference in how smoothly the engine runs, and a slight difference in power too over conventional oils… i have used it also in the 3100 SFI in my Century and it liked it too!
commonly people start using it thinking it will be a miracle cure too engines burning oil badly, or they think it will allow them to go all sorts of extra miles on a oil change, i doubt that, then people don’t use it as directed, add too much and they have issues… as for engines like some of the new honda engines with the 0-W20 weight oils, i would not add Lucas too that beacuse i feel its much too thick
additionally the transmission stuff is great, smooths out shifts in old transmissions that are a little rough simply beacuse the trans is old and gunky inside, but once your trans is starting too puke its done and over, it usually will not fix the issue.