Lots of choices, everyone has their own opinion, I use Mobil Delvac 1300 15W 40 in my 308.  Newly rebuilt about 5000 miles or less on it.

Much appreciated Calvin.  I am wondering if I put in detergent oil if it will kick up sludge from the oil pan than might do damage.  The engine has 45K.  Any thoughts about non-detergent 30W?  I use that in my Model A.

Oil quality has come a very long way since 1952. I would use a modern detergent oil, 10W40 or so. Add the recommended type of ZDDP for lifter/camshaft wear. Don't over do it!
Run for 500 miles and change the oil again to help get any sludge build up out.
https://pqia.org/2021/04/15/motor-oils-for-classic-and-vintage-cars/
https://www.speedwaymotors.com/the-toolbox/classic-car-oil-do-old-engines-need-zinc-additive/53637
https://gearscare.com/best-oil-for-old-classic-cars/

Good review on Engine oil. Thanks for Posting.

I guess it's time to repost this again.  Here are some technical considerations with the oil you choose.    

About 7 years ago, I was at Carlisle for a weekend Ford show. Joe Gibbs Driven had a tent set up. The presentation was given by their chief engineer (I forget his name). The main point of his presentation was to NOT use any aftermarket oil additives, and just as importantly, why. Of course, when you have access to a guy like that, you hang around after the presentation and ask more questions!  

It was a fascinating discussion, all the details of which I can't fully recount, but some important points: the highest pressure and wear points in an engine typically are the cam and follower contact, and the rocker to valve stem. These places have high loads that concentrate in a line or even point, with a wiping motion that tends to wipe off the oil film, so ZDDP is crucial at these points. Newer engines are designed with roller followers on the cam in order to reduce these point/line and wiping motions, because EPA regs have increased the time that emissions systems must operate correctly and be warrantied.   Zinc and phosphorus contaminate catalytic converters and O2 sensors, so in newer oils the ZDDP had to be reduced, forcing the cam followers to be redesigned to work with less of it.  It turns out that there are several dozen different formulations of ZDDP, "zinc," or whatever name you use, as well as the other additives (detergents, friction modifiers, etc.). The oil additives have to be designed to work together, so that they do not interfere with each other or actually cause some of the additives to precipitate out. Then you could end up with LESS ZDDP or other additives than you started with. Therefore, DON'T use any oil additives. 

Well, as everyone now knows, our old engines weren't designed for low-zinc oils, so we want to find oils with high ZDDP levels. Diesel rated oils became the initial go-to oil for the olde car hobbyists, because diesel engines didn't have catalysts until recently, so they had higher levels of it. However, you may also know that, in recent years, diesel engines have been fitted with catalysts and Diesel Particulate Filters (DPF), and sensors and controls, and consequently the ZDDP levels have been reduced for the same reasons. So just picking any old diesel rated oil no longer guarantees high ZDDP.  The other go-to is "racing oil" from Valvoline or Driven or other manufacturers.  Since racing engines don't have catalytic converters, racing oils can use more ZDDP.  

To further complicate things, the oil manufacturers change their oil formulation from time to time, and don't make widespread announcements about it. It's not a state secret, but you have to go to their websites and look up the oils and see whether anything has changed recently.  

Since that's a PITA, I've been using the Ford Motorcraft brand 15W-40 diesel oil for Powerstroke Engines. If you have good results with a particular oil, I won't argue. But I chose the Ford Diesel stuff because it says right on the bottle, "Contains more than 1000PPM of phosphorus (that's the P in ZDDP). Not for use in catalyst-equipped engines." Yeah, that sounds like the good stuff to me. I was using Delvac 15W-40 for a long time, and still use it in some other old cars, and I can't say I ever had a problem with it. But the label on the bottle doesn't tell you much. So I lean towards the Ford Diesel stuff. Especially when it's on sale at Walmart.  The racing oils are hard to find locally, so it's best to order them online.  Also, in the past decade or so, a variety of oils specifically for "classic" or "Vintage" cars or "hotrods" have come to market, and they all advertise increased levels of ZDDP, but they are scarce on the local auto parts store shelves, so you probably have to order them online too.  

Anyway, some things to think about when you go shopping for oil. And if in doubt, check the web site for the oil manufacturer.
_____________

Hi Dave, Thanks for the important information and sharing what you know and have found out through experience.
db

Much appreciated Kerry. 10W40 is the oil suggested by people's opinions. I will pull the pan and clean it also.

Info on using synthetics in oilder motors---
https://m.youtube.com/watch?v=pPFSR-2lhxY

Probably be a good idea to take down the pan and clean it out first

I'll update my post from last week with some current info.  I recently experienced lifter wear on another old car engine with rockers that ride on the cam.  Consequently, I went looking for the most current info on ZDDP content in diesel rated oils.  The oil I had put in it after break in was Mobil Delvac 1300 Super (not synthetic).  The Mobil web site did not list the zinc and phosphorus content.  However, I went to the Petroleum Quality Institute of America (PQIA) which regularly tests oils for their compliance with API ratings, and their ingredients.  It turns out that most current diesel rated oils have well less than 1000ppm of phsophorus and zinc.  They are in the 600-800 range.  This is way too low for the solid lifters and flat tappets in older engines.  You WILL get accelerated cam and tappet/follower wear if you use them.  Gasoline oils rated under the last few iterations of API requirements are also well below 1000ppm.  By contrast, the commonly accepted ZDDP content for safe use in flat tappet engines is between 1000 and 1500ppm.  

According to my searching, the Ford Motorcraft Powerstroke Diesel 15W-40 oil is safe for our cars because it has well above 1000ppm phosphorus and zinc.  Some other common oils in the 15W-50 viscosity grades also exceed 1000ppm, but I would rather stick with something that advertises right on the bottle "exceeds 1000ppm of phosphorus, do not use in catalyst equipped vehicles."  The others may change their formulations without prior warning.  You can buy the Ford oil at most auto parts stores, as well as WalMart.

Your other options are one of the specialty manufacturers who formulate oil for "classics" or "hot rods" or "racing."  Unfortunately, you probably will have to order those online and have them delivered to you, so you need to do that in advance.  Some good options in that category are, BradPenn, Joe Gibbs Racing Driven, Valvoline racing oil, Lucas, and several others.  

EDIT Update:  I'm seeing the Valvoline VR1 at my local NAPA stores.  That's a good choice too, with 1400ppm of phosphorus or thereabouts. 

For those who want to see independent oil content test results for themselves, here is the PQIA web site.[url] https://pqia.org/ [/url]

[b][size=100]Peter
Go to BOBISTHEOILGUY.COM and check out the VOAs for what additives are in hundreds of different oils.[/size][/b]
 

Been reading that site for years, way before it was sold. I started doing oil analysis because of the info I read.

Multiple video's on You Tube talking about issues with new cam and lifter wear. Seems over the last 10 years or so it is very hard to find quality lifters. (most of the time it is not the "oil")
Most of the NOS ones are dried up.
https://www.youtube.com/watch?v=ycb8Yy38DwU
https://www.youtube.com/watch?v=eYv2Az3_KfU (go to 8:20 of this one)
https://www.youtube.com/watch?v=MbRjAMhCEJk
https://www.youtube.com/watch?v=7M-yopGZO94&t=20s
A lot more then these are posted-----

Thanks All, I bought Valvoline 10-40 and I will pull and clean the pan.