I have been a Lucas user in all of my diesels and vehicles for over 15 yrs. and I have seen mpg improvement and oil pressure/temps are better too in the big trucks and all of my vehicles no matter what anyone says.... It is costly but, I personally think it works..... In my 12 gal oil change in my CAT(s) - I use 3 gals of Lucas Oil Additive everytime.... Thats a 10K oil change every time in 15 yrs. in the big trucks.... Just my $.02.... It works....
I have in my trans and rearends, power steering, fuel additive, fifth wheel and slider lube, transfer cases, anti-gel too, etc..... On my guns.... In the engine and transaxle of my pulling tractor too.... I use it all.....