Piston slap sounds?
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Trunion King
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From: Texan in Colorado
Piston slap sounds? What is the sound does it make? Slap, slap, slap? When does it occur most of the time?
I'm asking this because I hear something like a knock during my cold starts but I doubt it's a knock because it goes away when the engine warms up. Car runs fine other than this weird noise it makes.
I'm asking this because I hear something like a knock during my cold starts but I doubt it's a knock because it goes away when the engine warms up. Car runs fine other than this weird noise it makes.
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TECH Senior Member
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From: Vancouver,[KITSILANO].B.C. Canada *WestCoast*
I have always used CASTROL/VALVOLINE/MOBIL 10w30 and mine sounds fine...I do not believe in this thin oil crap... 
.........everybody says use Synthetic..like vettes and vipers etc...I realize clearances are closer in these more modern cars....but good 'OL DINO OIL works just fine...[ I am not racing] 
.........everybody says use Synthetic..like vettes and vipers etc...I realize clearances are closer in these more modern cars....but good 'OL DINO OIL works just fine...[ I am not racing] LS1 Tech Stories
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I have the same problem in a 99 Z28 I just bought. When I bought it the guy said he used 10W-40 he thought. But then he said he used whatever the book called for. The car was quite with whatever he had in there. The oil had not been changed in 7 months so I changed it to Mobil 1 10W-30 because that is what the book called for. Now I have a knock when cold that goes away. I called a friend at the dealer and they say 10W-40 is not a good idea to be used. I really don't know for sure what the other guy used because he could not remember for sure. The car only has 48,000 miles on it. Any thoughts on this piston slap and the weight of the oil. I have a 91 Chevy show truck with a new Goodwrench engine and it does the same thing but it is a little bit louder. I have been told it is normal.
Actually, from my understanding would that not be better? If the piston is too small and it expands under operational temps then it would be correct! The engines DON'T make noise under op temps, right?
That's a hell of a lot better than them being the correct size cold and seizing against the cylinder walls when warm.
That's a hell of a lot better than them being the correct size cold and seizing against the cylinder walls when warm.
I just thought it was odd that I did not hear the noise until I changed the oil to 10W-30 Mobil 1. It started the very next day. If it doesn't matter about the noise I will try and get used to it. I am just worried about it in the long run. I don't have any warranty and I don't want to run into a problem.
