I noticed a loud rattle inside my engine during cold starts recently after changing my oil. The sound is there everytime I start the car in the morning. This was my first oil changed with the car and I used Castrol edge titanium. I don't recall hearing this sound before the oil change. The sound is so loud that it worries me a bit but it does go away when the car warms up and it drives perfectly fine. My last ap1 had it but nowhere near as loud. Would there be potential problems in the near future?? Maybe a valve adjustment might lower the sound? I get so paranoid that I don't even rev anywhere near vtec anymore.

Should I switch the oil to something else? Original owner told me he used Mobil 1. Any other ap2 owners with loud piston slap during cold starts? The car is an 05 with only 25k miles. Previous owner barely drove it and let it sat most of the time if that has anything to do with it.

 

Sounds like a TCT problem, do the sandblasting DIY, I just used some sound paper on mine, noise on start up went away. My ap1 has some piston slap when cold, as soon as it warms up it goes away, same thing with a buddys ap2, but I would do the TCT sanblasting or Billman replacement anyways.

 

Have someone else start the car while you listen and try to isolate the sound. Record it if possible so we can hear it.

If you haven't had the valves adjusted yet, do it!

 

Piston slap is not oil related, it is a mechanical issue with your engine. Some oils can reduce the related noise more than others but you will never get rid of it simply by changing oil brands. I have read reports of other S2K's with the same issue, if I'm not mistaken they were all ap2's ?.

Piston slap is actually relatively harmless despite it sounding somewhat nasty. Quite a few domestic engines that are famous for piston slap have been known to last a very long time without issues. Just give it a proper warm up and don't drive hard or with too many rpms until the engine warms up and the noise settles down.