5w30
It depends on make/model/yr, what you want from the turbo kit, how much power you want, rpm power range. A T4/T3 50trim up to (475hp). a GT3782 or T61 to (525hp)Bullseye/borg warner s258 would work to 650hp.
From the factory i believe it's pushing 425hp. majority of the c12's are 435hp. with a tight rack and ecm tweaking you can get 475hp.
about 475hp, 550 torq
There are three things that cause loss of oil pressure: worn-out oil pump, worn-out springs on the pressure control valves, and worn bearings. (Listed in order of expense to fix. Worn bearings means you've got to do an in-frame overhaul on your engine.)
Stock? No, for many reasons - not limited to: tires will not handle that speed, electronic governer will not allow the car to get much beyond 130, stock transmission/rear end will likely not be able to get there safely (may be able to get there, but probably wouldn't survive long). With some modifications? Absolutely - but it will be expensive. -snip- The above isn't entirely accurate... A: the tires on my SRT-8 Charger will go 200mph, Stock they are Goodyear F1 Supercar tires. B: The electronic governer stoped my car at 180 but with a quick edit with the DiabloSport tuner that is fixed. C: The stock trans and rear end are from a MB E class and can easly handle 1000 + HP.. They are bullet proof. D: The Mods I have done have cost me about $1000.00 and I now have about 475HP at the wheels and can swiftly get to 200+ mph