Oil change?

I was wondering how much oil should a 5.7 engine need? I would assume that It would be 5qts. which is all it took, but apparently it has a oil cooling system and requires a larger then normal filter, but with the cooling system and larger filter wouldn't it take more than 5qts.? And what should my oil pressure be? This last oil change I put mobile 1 in and when it is running cool the oil presure is around 60psi but after it warms up it drops to around 40 psi. is this normal when using a full synthetic oil? Thanks.   

DEPENDS ON WHAT THE VEHICLE IT IS IN.  IF IT HAS STOCK OIL PAN.  SHORT OR TALL FILTER.  OIL PSI CAN BE ANYWHERE FROM 25-40+ PSI AT IDLE.  

I have a 2006 silverado 5.3 liter and I just did an oil change today. I used mobil fully syn. and it took 6 quarts. I would think yours should take at least 6 quarts, but read your owners manual under specifications/ oil capacities.

I guess it only takes 5qts. Every time I check the dipstick it show that it is at the right level. The engine is in a '95 1500, with an oil cooler system. It just seems odd that oil presure would only be at 40, but then again this is the first chevy I have owned and the first time I have use Synthetic oil in any of my vehicles.

5 qts of oil including filter is correct for the 5.7.  You've got good oil pressure, it is right where it should be for that engine in very good condition. Different oil brands or wieght ( 5w-30, 10w-30, 10w-40, etc..) won't make the pressure vary all that much.  The pressure will drop slowly over time as internal engine components wear.  Really low pressure  (<15 at 2000 rpm) on a fully warmed up engine usually means worn crank bearings and piston rings. A major rebuild or short block would be needed. Regular oil changes with quality oil helps minimize internal engine wear, and oil pressure loss. My 98 silverado with a 5.7 vortec when it was new, had oil pressure of 50 - 55 psi warm at 2000 rpm, 70 - 80 psi cold at startup. I changed the oil every 3000 miles and always use 4 qts 5w-30 valvoline duralube synthetic blend and 1 qt lucas heavy oil stabilizer. I'm at 225,000 miles having done nothing but scheduled maintenence. The oil pressure fully warm at 2000 rpm is around 35 psi. Cold pressure around 50 psi.  I'm told by my local Chevy service department anything 20 psi or >  fully warm at 2000 rpm is within safe operating oil pressure specifications.  Hope this helps.

Thanks for all the help, now I know.