? About a 98 Stang GT, "Slight Knock :O"

94SCBird

Registered User
My friend has a 1998 ford mustang gt with a 4.6 SOHC and its got around 122,000 on it, and he was driving it to work one day not really hurting it but drivin it normal and all the sudden it started to get a little knock, and i never heard it until today we decided to change the oil in it and see if maybe it'd go away, we talked to one of the guys that owns a carquest here in town and he said that it was the synthetic oil he was runnin in it, he said that stuffs disasterous on a 4.6, and i heard it finally and it only has a knock around 2 grand, and then it starts to go away, and you cant really hear it at an idle, and if you do you have to be crouched down by the drivers door to hear it, he thinks its a rod knockin im not sure really cuz i dont see how it can knock at 2 and not get worse when you rev it up more and theres nothing at an idle. he's talkin about pullin it and rebuilding everything and im tryin to get him to have somebody look at it to make sure, and i was woundering if anybody out there knew of a good mustang mechanic in iowa.

thanks keith
 
there was Piston Slap in my girlfriend Acura that made a knocking noise at a certain RPM and not below or higher that a certain range. maybe its that ? i sold it to some dude he was working me down on the price of my already lowered kbb price. he thought he worked me, but really he didnt ;) he never heard the noise since you only hear it at a certain low rpm range. :D
 
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Synthetic oil a disaster in a 4.6? I wouldnt go to that Carquest for advice anymore after hearing that. My 01 4.6 truck got nothing but full synthetic from when I bought it new, until I traded it in 05 for a new truck. It never knocked or anything silly like that and I towed with it and treated it like a truck. Spent lots of time at Ford Truck World and they never had trouble with it. My Dads 96GT never had trouble with it either.

I had an A/C compressor that knocked at higher RPMs once.
 
I have heard not to put anything in a 4.6L but 5W or 10W 30 synthetic or not. 10W40 and 20W50 were bad for it. Maybe?
 
You are correct about the weights of oil. The new ones are strictly 5w20. Mine was just fine on 5w30 synthetic though. My new 5.4 3valve only gets 5w20 though, just to be safe.
 
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