Engine oil selection

[Real Auto Dynamics]

I'm live about 50km from Cape Town and you? I use the car daily with the occasional sprint (would like to do a trackday in the future). I don't know what the internal specs. Still trying to find out the history of the car. The piston slap seems to almost go away when the oil is on temp, but i'm new to all of this... i'm used to 8v opel noises :lol:

A technician from Subaru advised to stick with 10w-60

Perhaps you should stick with 10W60. If you are hearing piston slap when the motor and oil is at operating temperature and you are using 10W60 oil, then that motor was spec'd and assembled improperly IMO. Do you consume any oil?

 

[Real Auto Dynamics]

Very interesting read, thanks for the info.
The above is what i dis when selecting my oil however I had some dead ends so i decided to change the grade die to my application. My piston slap has reduced.

I se u mentioned multigrade, I'm running Fully Synthetic. Any comment or pro's and con's on this?

I prefer a good synthetic like Amsoil, Motul or Redline. If you are using a conventional oil then you just have to change it frequently.

Synthetic oils have better properties all around and are likely to work better under extreme conditions

 

[ruan]

It does consume a little bit of oil. How do i know the difference between piston slap and lifters(asuming the lifters can be heard on a subaru)?

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[HolyCrapItsFast]

Lifters would be a rapid clatter unless it is just one. Like marbles. Piston slap is like a thud that coincides with the rotation of the motor. This doesn't necessarily mean it is a bad thing depending on what the engine was built for. For daily driving and occasional track days, it is not desirable.

What kind of horse power are you putting down? I usually never recommend anything other than a stock block on anything 400HP or less combined with a good tune.

 

[ruan]

Then I think it's the lifters i hear. I still need to get the car on a dyno. The previous owner said it's doing 250kw which is about 335hp

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[Piper86]

Wow thats strange as i was advised on 5w40 by subaru again. Anyhow doubt it would do damage. I'm in Gauteng. You should do a gymkhana/skid pad event. Its a lot of fun and you can learn a lot about the car. Plus low wear and tear compared to track day

 

[Piper86]

Lifters would be a rapid clatter unless it is just one. Like marbles. Piston slap is like a thud that coincides with the rotation of the motor. This doesn't necessarily mean it is a bad thing depending on what the engine was built for. For daily driving and occasional track days, it is not desirable.

What kind of horse power are you putting down? I usually never recommend anything other than a stock block on anything 400HP or less combined with a good tune.

Piston slap not desirable due to noise or why? I thought this was just a normal thing with forge motors. Im making below 200wkw and I've been told my noose is piston slap
How ever the built can handle almost double what I'm doing now if i go bigger turbo. Or so i was told

 

[HolyCrapItsFast]

The piston slap should go away, or be barely noticeable, when the motor is warm. The pistons are supposed to expand to the correct piston to wall thickness and that is usually around .002 to .003 in most built motors but that can be much higher for very high boost motors. The ring gap is usually what determines boost capacity for built motors. Another contributing factor to piston slap is cylinder geometry. So often do I encounter blocks that have not be torque plate bored and honed and when the heads are bolted down the cylinder become egg shaped or deformed and the piston doesn't sit in the cylinder right. That condition is usually followed by ring sealing issues.

At the risk of making a controversial statement and offending some, Built motors are stupid IMO unless you are going to use them for what they are built for. Most people don't and they just go with what is subscribed. It is usually someone selling you on overkill parts that make them allot of money.