Adding stuff to your oil isnt a very good idea, especially if you don't know how the stuff you're adding will react with the oil itself.
If you really want to 'clean it out' do a 100 mile oil change on cheap synthetic.
If you really want to add something to your oil, LiquiMoly Mos2 is proven to be very effective.
I never used lube guard so I can't comment, but I very much doubt it will do anything an oil meeting 505.01 can't do