Cold vs. oil pressure

Morning all,
So on this nice 16 degree morning here in the bluegrass state, I decided to fire up the mustang because it hasn't ran in a bit and the oil pressure gauge and myself had a little discrepancy. Usually, the oil pressure shoots straight up to 80-85 until warm. Today it went to 60 on startup and slowly crept up to the 80 mark and was fine after that. The 460 has a melling hv pump in it I have 10-30 in it for the winter months, obviously summer I'll go a little thicker. After it reached 150 degrees or so the pressure was down around 50psi or so and ran up to 80 psi when held steady anywhere between 1500-2000 rpm. The usual pressure for this motor at full operating temperature is around 35-40Psi at idle and 75psi+ anything above. The oil is fresh, maybe only 4-5 hours or run time on it. Btw, op gauge is plumbed to the port on the top back of the block (where it seems to be the most important).

Does this sound like just cold thick oil taking time to circulate to you guys? The only reason I ask such a novice question is because I know how important the op is in these beasts because of the unorthodox path the oil has to take through the motor. I just don't want to cause any damage to the ol' girl.

Thanks in advance, fella.
Jeremy

when it first fired and you noticed the pressure was slightly down from where you usually see it on cold start up was it idling at it's usual rpm right then? If it was even a little low or missing a little (fat and cold blooded) it might've caused the discrepancy until it evened out, was hitting on all 8 steady and you see your normal cold psi. After that the slightly higher psi I would think would be due to the cold temp's. You probably would see everything as you are used to after getting some good heat into it.

What size line runs to the gauge? If it is the small plastic or copper line, the cold/thick oil was having a hard time being pushed through the line. After the oil warmed up it was easier to push through the line.

4thhorseman, it's kind of difficult to get the car to start in colder situations because of the race carb so I had to give it gas for about 2-3 minutes before it would idle fairly well on it's own. Hovered it right around 1500 rpm for the most part with a little fluctuation. It took maybe 45 seconds to a minute and a half for the pressure to get up to 80 which doesn't seem long but I'm used to it just hitting 80 from the get go. Even once I let it go on its own and it was idling rather roughly it still held onto about 75psi around 550rpm.

Nord315, and supervel45, those are good thoughts. The car does still have the plastic/nylon style tube on it, which scares me to death lol. That's a pretty good possibility. Looking to change that bad boy over to steel braided line when the weather becomes less miserable and more tolerable.

Thanks for the replies fellas

Yup ss line is one of the things at the top of my spring "to do" list. I've heard all the horror stories about the nylon lines rupturing and whatnot, and I want absolutely no part of that noise! Lol. I hope it warms up too man. I was outside doing work about a week ago in 65 degree weather and a sleeveless shirt......now there's 4 inches of snow and ice on the ground. That's the ohio river valley for ya.