Don't go too thick, you can open up your bearing clearances. Use what is specified for your vehicle and what its used for.

Rotella really isn't a good choice. Neither is gear oil or mineral oil.

here is a app for oil selection

http://classic.valvoline.com/crmo/vehicle.asp

Use a additive product for the zinc content you want for flat hydraulic lifters.

Don't use the synthetics for engine oil. Great Lathe oil, drill press....