need some advise

[ny mustang gt]

i just bought a new o1 gt with the 4.6 and was wondering im running the recomended oil 5-20 in it the second oil change was done the other day is there a syn i can use found none out there in that weight but the real reason im writing two is that the car seems to have what i thing is a ping i brought to the dealer the other day to check it out and they said nothing was wrong but i went under a bridge and you can here that sound i dodnt know if its pinging but it just doest sound right do these 4.6 are they like that is it soilenoids noise injectors i have know i dea so im hoping someone out there can help me i would really appreciate there input and help because i really want to mod my engine out as all mustang owners do but im a little hesitant on the what dosnt seem to be a car that sounds like it has 260 ponies thaks a new member to the ford family

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2001 4.6 gt