Hi I recently had some work done on my suburu remap while it was being remaped the workshop tech guy said theres no rattle on my pistons I thought no play the better evidently not according to this guy is he talking out of his **** ?

Talking about piston slap I think mate

Forged pistons do normally rattle a bit when cold. due to needing bigger clearances to allow them to expand when they get hot running high power [emoji6]

+1 mine do however mine are exceptionally quiet for forged units, What oil are you using ?

5 30 vavoline

My pistons are cosworth he just done a power run then he remarked on the rattle ie no rattle .had them fitted 2200 miles ago now think they should ave been warmed up by doing the power run thou ?

5 30 is way to low for forged pistons. this could be your issue, im bedding in on 10 40 and moving up to 10 50

So I should use 10 40 and for how long

im using 10 40 for the 1000 mile run in then switching to millers 10 50 for the foreseeable

Think I change mine to 10 40 then 1050 ty for help

have your pistons been run in  ? if so id go straight to 10 50

Yep run in now got 2300 on them now ty I go to 10 50 cheers mate

What grade oil is always a can of worms lol , but if your cossie pistons don't make a noise when cold (like tappets) then I'd say that their running tight ish clearances ,So I wouldn't jump to many grades of oil at once .

Mabye see how a 10w 40 goes as it will only flow slightly slower, but will only be a grade thicker @ 100°

I do agree with ash as well [emoji106]

as i used millers 10 w 40 running in oil (mineral) and then switched to 10w 50 millers nano drive fully synthetic .

my mahle race spec pistons are only running half the power their set for and are noisy up to 90° oil temp .

But ,just like the wife, they shut up and do their job well when I spank em [emoji39]

As Savage said. :)

 

Did your engine rebuilder not tell you this when the pistons went in ?

I went back to them when I had 1500 on them he did a oil change n filter he put in 5 30 I bought car of a dealer and two days later pistons went hence why I got cossie pistons anyhow it was under warenty no he didn't say about change the grade of the oil .