DO NOT flush the engine in an extrely high millage car...all that carbon and crap is taking up the slop in your otherwise worn parts..if you do flush you will hear all kinds on neat little noises you never heard before...you may also notice a nice signature wisp of blue smoke trailing behind you as your valve guides will now be nice and clean.

the same can also be said for older radiators...you will have leakes you never dreamed of..

 

i used it in my 97 gt with 150,000 miles on it twice...at first i heard a little noise that was noticable but after a couple days it just went away but my engine still runs strong. maybe im a lucky one, who knows