The break-in oil allows more friction in-between the moving parts so parts get mated nicely.

There are a few companies that sell them

Just grab the oil and not the additive alone

 

From what I've read Subaru doesn't use break-in oil, just conventional oil from the factory (Nisseki-Mitsubishi M1K 5w-30).

From here: http://forums.nasioc.com/forums/showthread.php?t=499177

 

From what I've read Subaru doesn't use break-in oil, just conventional oil from the factory (Nisseki-Mitsubishi M1K 5w-30).

From here: Oil FAQ: Read if you want more information on oil, oil filters, and oil changes! - NASIOC

From the factory, the engine is run for awhile using break-in oil prior to installation, usually about the duration equaling a thousand miles prior to drain and factory fill of standard oil.

I think the OP is concerned with a new engine and not an engine in a new car as they have an 05.

 

they motor will be freshly rebuilt and built with better parts...so im trying to see if this additive is sufficient since i have it on order...

 

Whether Gunma or Indiana, Subaru does not use a break-in oil. The only thing unusual that a used oil analysis will show is high molybdenum which comes from the assembly lube and the pistons.

If you're looking for a break-in additive, try Red Line.
Red Line Synthetic Oil - Motor Oil for Racing - Engine Oil Break-In Additive

Brad Penn has a straight grade break-in oil :
Penn Grade 1 High Performance Oil

Most straight grade conventionals are good break-in oils. Castrol also has straight grades and I believe Rotella does as well.

Also find out what your builder recommends.

-Dennis

 

i am the builder. and since the cylinder walls are getting rehoned im in another league not concerning what subaru does with their engines. this engine NEEDS TO BE BROKEN IN. im just going to go with a mad cheap conventional non detergent oil. and research this additive more later. thanks

 

Why go with "mad" cheap conventional oil. You just spent all that money to build your block and your gonna put the cheapest $hit in? I for one never put anything cheap in my cars to protect my investments. I'd spend the extra 20 doll hairs for the piece of mind.

 

Cheap is actually fine if you're using something that will hold up like a straight grade that I mentioned (like Castrol HD 40, Rotella T1 SAE 40). There are no viscosity index improvers in straight grades, which are the first thing to break down in multi-grade oils.

-Dennis

 

exactly not only that i will be changing the oil after 20 miles. i will buy dealer oil the first time around after changing the oil so soon. learn yourself good son!