Take it to Doug and the guys at STechnic.
very smart bloke with subies
owen wrote:redline gearbox and diff oils - not cheap
spark plugs were about 30 bux each
RE: redline,
I've had it on good authority from my gearbox builder who replaced my stuffed 6speed centre diff that redline does more harm than good in a VCD subie box
something about excess heat transfer to the VCD causing premature failure of the viscous goop. and by nature of it's "stickiness" can cause issues with the soft 6speed synchro's
and $30ea for plugs, absolutely flogged.
turbo and high comp motors (especially gen4 Subaru's with sh!t factory tunes that ping their heads off) care not how expensive your plugs are, detonation will take chunks out of the ends of them whether they're $3 copper plugs (recommended) or $30 iridiums
when the engine detonates it takes pits out of the tip of the plugs. iridium/ platinum plugs have super-fine tips, and removing ANY of that material causes issues with opening up the plug gaps, then you get misfires and running rough.
Use $3 NGK Copper plugs, just replace them frequently and save your cash