you sure you really need that additive? (lucas)
probably isn't doing much harm, but probably isn't doing any good either...

http://www.bobistheoilguy.com/images/lucas/lucas.htm

I also googled some used oil analysis that confirmed (mild) increased wear with the lucas... sorry don't have the links..

On the other hand seems like their upper cylinder lubricant fuel additive is a product with some tangible good results...