Cold Piston Slap -- Oil & Additives

[suubyduuby]

Have just been reading a bit on CS once again about the issue with cold piston slap on the Leggy EJ20TT engines.

My 99 BH5 (EJ208) has a noticeable cold piston slap when cold, but goes away after a short amount of driving as the engine warms up. From what I've dug up on the forums and net research, seems like a common issue with some of these motors. However, it seems clear that oil choice and engine additives can also make a difference to resolving this problem.

Normally I let the car sit for 30 sec to a min when its cold in the morning and then drive it.

I'm currently running Shell Helix Plus 10W-40, but have run Castrol Edge 5W-30 in the past (as recommended by Subaru - can't remember if this made a difference though when cold?).

Anyone found that the issue is aggravated/relieved by certain oils? I'm guessing its not a show stopper though - from memory I remember reading it was something to do with the semi-forged natured of the R/H bank pistons which are slapping against the cylinder wall until the tolerances are met due to heat expansion... ???

Would be keen to hear people's thoughts on this... :

[Bazza-NZ]

next oil change add in MBL8, that should help, Mine also had slapping on cold morning but it does away, MBL8 didn't remove it completely but made it less noticeable

I use Castrol Magntec 10-40W and have found it to be very good for my car, some issues i found with other oils is the car wouldn't run well, it would be loud...

MBL8 is added to the last 1 liter of oil you add into your engine then run it for 30 mins, Will help your engine a lot, will run much much more smoother

[funkytown]

dont be confused with noisy lifters..

these also get noisey when cold and when oil is old, replacing the oil makes them much quieter..

[suubyduuby]

 funkytown said:

dont be confused with noisy lifters..

these also get noisey when cold and when oil is old, replacing the oil makes them much quieter..

Tru tru...Normally do oil every 5k, and does it even after a fresh change...

MBL8 sounds interesting though...has anyone else using it?

[Guest boostin]

IMO its a Band-aid. If you need to use it, your engine has issues that need to be fixed mechanically.

[suubyduuby]

 boostin said:

IMO its a Band-aid. If you need to use it, your engine has issues that need to be fixed mechanically.

Fair enough comment - but correct if I am wrong, you can't really do much about cold piston slap can you? Apart from new pistons with better skirting tolerance when cold...?

I mean...I've heard of engines that have had piston slap their whole life with no problems. Believe it was a but of an issue with some of the 2.5 engines shipped to usdm vehicles as well....

Was Subaru supposed to fix the piston slap on the EJ206/208 engines as part of a factory warranty fix?

[ReubenH]

Meh, maybe go to thicker oil? don't listen to me though, i run bloody 10w-60 with my forgies, and they still sit there rattling away like buggery when not very very hot.

[suubyduuby]

Hmm...found this on Youtube, very similiar if not identical sound:

The guy reckons though he's had his for another 40,000kms and still going strong. Just annoying that's all.

Some of the comments:

"Just want to post an updated comment since I've gotten so much feedback... apparently this is NORMAL. My cars been running strong for over a year now and 40,000km later, not a problem. So relax and enjoy the car. :)"

"I have a 2008 WRX with 7500 miles. Same noise when the engine is cold, but it gets quieter when warm. From what everyone's said, it's nothing to worry about, but since mine is so new, I'm going to swing by the dealer."

"Same issue here... 04 WRX.. goes away when it warms up just a normal Subie sound"

[Guest r0ksta]

Ive got this on my 96 RS that ive just recently bought, its perfectly normal. My old 97 WRX STi did the same but it went away once it warmed up, nothing to worry about, but the guys at the AA Inspection place thought the thing was going to blow up in front of them when they checked it out before I bought it, shows how little they know or how through they are.