what would be the best way to determine an oil leak? i just recently replaced the intake manifold gasket, so i'm pretty sure that one is not leaking. however, i will double check the back of the manifold later to see if there is a leak on the backside. but in the meantime, provided the intake is not leaking again, what would be the best way to find a leak. can i take it somewhere and get the engine cleaned? or how would i go about doing it myself? thanks guys.
dave

edit:
also, when i changed the intake gasket i switched to 15w50 (mobil 1 synthetic) and my oil pressure has been extremely high. i was assuming that this is due to the fact that the temp is cooler out and that it is a thicker viscocity. but now i dont think so anymore. its pegged all the way to the right at start and then when it warms up it settles to a little over halfway. i dont think this is right. before, it was down to a 1/4 pressure at idle. even at start up. any ideas. i checked the oil pressure sensor at the back of the intake and it seems clean and plugged in. any ideas?

 

Put die in the oil and use a UV light. This will eliminate you mistaking oil that is already on the block from being your problem. Most times the sun will do instead of the UV light. Be careful if you clean the block and stay away from the front if you can. Die and light kits are available at most tool retailers. Most mobile tool retailers will give you the die for free since it's cheap to begin with.