If piston slap is the problem, I don't think the additive will fix it. Mine is at the dealership now. They're going to cold start it tomorrow and see if they can hear any unusual noise. I'll let you know what they come up with.

 

i bought my 99 a couple of weeks ago.when i bought it it needed an egr valve so they replaced that.i asked him about the motor knock during start-up and he said its "normal for these tritons".he had two other ones on the lot and they did the same thing.he told me if it did it when it was warm then they would replace the motor.thank god i got a two year warranty i guess.

 

i have a 1997 e250 super with a 5.4 has had a slight lower end knock since day 1. but noticed after switching to synthetic oil of a heavier weight it was almost gone . i have used 20/50 during the summer and 10/40 in the winter also swear by my remote start and i use it all the time. after 300,000 of hard miles (i am a very hard driver) it still runs strong.... only have replaced radiator at 200,000 and alternator at 215,00. original transfluid from factory still reddish. lol I definately got my moneys worth and is the most reliable vehicle i ever owned!