oil pressure fluctuating.

ok, just got the car fired last night for first time since changing to efi and roller cam. oil pressure was steady bat idle about 50 psi, but as engine temp raised the oil temp went down fluctuating between 25 - 40 psi and came back up to 60 as i brung rpm up to 2500 and stayed steady. oil temp was just under 140 and engine temp 190.i put bradd penn 10w 40 in her. cam and lifters are hughes hydraulic roller. they say to run 10w 30 with their lifters.
i'm thinking oil is thinning out at engine temp.