i use:
motul turbo light 10-40w engine oil, works a treat!
ryco oil and fuel filters, they've never given me any issues.
as for spark plugs; the rb20 is fussy with spark plugs. a few friends and i found the NGK BKR7E to be the best for the rb20, and are only a couple dollars each. i also tried the NGK BCPR7E but didn't like those, they caused slight misfiring. i have a set of NGK platinums that i brought a while back, which i wasted a good $110 for as they are completely crap and kept misfiring. if you do decide to go with the BKR7E, make sure not to get the BKR7E-11 as they're a 1.1mm gap and will get blown out during boost. it's trial and error with spark plugs.
any high rating radiator coolant will do fine.
and redline shockproof for the gearbox.
make sure to change engine oil and oil filter every 5,000km, fuel filter and spark plugs every 10,000km.
my2c!