I'm pretty sure that Lucas has been around as long or longer than Slick 50 or Duralube. I remember seeing it in the stores at least 10 years ago. I also think additives like Slick 50 and such will help protect better than conventional oil alone, though maybe not as well as a full sythetic.cary said:No chemical change is going to occur in gear fluid when run in a box short term as there is no cumbustion. It will get warmer but little else will happen.
People have run UOA's using Lucas and not using it on the same car, same oil, same interval and consitantly the Lucas causes there to be more wear metals in the engine.
I stand by my statement Lucas is snake oil. It is simply an oil thickner. Do your really think if there was some magical property to the stuff that Mobil/Exxon, Shell and all the other oil manufactures wouldn't have adopted it years ago? By dumping that crap in your oil, crankcase and other areas, you are basically saying that you believe that Lucas and you know more about lube design and blending than the manufactures that make the lube oils. Mark my words that in 10 years Lucas will be like Slick 50, Duralube, STP oil treatment, and the 50 other snake oil products that are out there. It doesn't cause any real harm, but it does not improve the oil you are already using and costs you money.
I did a test about 10 years ago with Duralube to see if it actually helped my mpg. I tracked my mileage for about 10 tanks before and 10 after and noticed about 1.5mpg improvement from what I recall. It wasen't a huge difference since I was getting about 34 mpg in the car I was testing, but it was still an improvement.