Oil pressure question

[Trans-Am Jim]

Got a crack in my oil cooler last time out this year. Really came as no surprise; it's as old as the car (19 yrs.) and I've had it out a few times and inadvertantly dropped it once.

Installed a new Mocal 13-row and noticed a change in oil pressure at start up and when car is not fully warmed up. Previously, it had been 80-90 lbs. at cold idle, then dropped to 60 when at warm idle, 80 at 3,000 rpm. Now, with the only change being the new cooler, it's 50-60 lbs. at cold idle, then when warm is back to 60/80.

Specifics are 65 427SO, Melling HV, Canton pan, #10 AN lines. Oil is 20/50 Valvoline VR1 dino.

I'm not concerned; mostly curious as to why a new cooler would reduce cold idle oil pressure by 30 or so pounds? And yet not change hot the hot pressure range of 60 - 80.

Anybody have an idea?

[a427sc]

Probably flows better, thus less restriction cold. When warm, oil flows easier in both and oil pressure determined by engine restrictions.

Don

[A Snake]

Don's probably right. I'd guess that the cooling tubes in your oil cooler are bigger than the old one or there are more of them flowing oil.

Al