08 fx35 104k miles engine knock IMMEDIATELY AFTER OIL CHANGE. PLEASE HELP

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Froogleprinting

Member
Location
Staten Island NY
Name
Seph
I purchased an 08 fx35 from a used car dealer 2 months ago. ! I love it. I went for an oil change at a local shop. I put 5w 30 castrol syntec highmiles and Lucas oil stabilizer. I drove about 15 miles and noticed a KNOCK. I thought it may be a bad filter or maybe the shop used that junk oil and fooled me so I immediatley flushed it and put the a another 5 quarts of castrol syntec and a new filter. Knock is still there. I was thinking the perhaps the car dealer I bought it from put some miracle oil in there and sold it. But I also spoke to a friend of mine that has an 08 g35 that went through the same thing but found out that he had to put ester oil from the dealer and problem solved. I have a warranty but would not want to go through the aggravation if it is something small. Any suggestions out there??
 
Knock is usually fuel and not oil. Are you using premium unleaded in the car?
 
Define the knock. Is it an actual knock when the car is still cold that gets louder with rpm? Or is it a marbles in a can sound when you're under load. Two very different things. If it's rod knock, you may have a problem. if it's just the marbles in a can sound under load, use better gas.
 
thanks for your help. It is definitely not a TICK TICK. i use high octane and fuel cleaner every other time i fill up. I do not hear it at first start up bc the idle is a little higher at start up. When it is warm is when i hear a knock (only between 900 - 1,300 rpms) anything higher than that i am sure the knock is still there but it get lost in the sounds of the engine when i Rev. It sounds like a heavier rod like knock deep within the motor. My only conclusion is that before i Purchased the car they put some MIRACLE OIL.

I am a little confused because there at times that i do not hear it at all. my friend did mention to me the ESTER OIL but i am not too sure about that.

2008 fx35 104k miles
 
When you changed the engine oil again, did you happen to see any particles in there? If it is rod knock, it's often caused by spun bearings and that leaves trace in the oil.

Dealer may have used a really high weight oil to quiet the knock. But maybe not since you used Lucas oil stabilizer which does effectively the same thing and you still heard the knock. If you have a warranty, I'd take it in and get it looked at.

Ester oil isn't going to fix the problem, it's not special, it's just a different kind of synthetic. It causes seals to swell which may prevent leaks, but it would do nothing for your situation (it's used in AC systems for the seal conditioning). Almost all synthetics contain some ester, but it's main advantage is thermal stability which again doesn't help your situation.
 
I was playing around with a snap on scantool and noticed that a common issue(as in they have a Bulletin for the FX) is a ticking/knock at idle... they say to look at the fuel dampner and hose... Mainly to replace it... If i remember correctly... fx35 is on the passenger side of the engine.
 
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