Oiling Antiques (general mechanical question)

Howdy folks,
I haven't been on OLDIHC in a while. The "Green Geezer" project (56 S-102) is running fine and for the most part complete. I've even acquired a set of original 56 California license plates for it.
While looking online for a special license plate frame, I stumbled across another project. This time it's a 1951 Nash Ambassador Custom. The body is strait and it runs strong, even though it's been sitting since the late 1960's. Upon careful examination I noticed that there is NO OIL FILTER! Since it's unknown when the last oil change was, I was thinking that it would be a good idea to do so. So my question is; would I be better off using a non-detergent oil since there is certain to be an unknown quantity of crud built up in that block over the last 63 years? The service manual only recommends 20W oil without differentiating between detergent and non-detergent.
Any thoughts?

Pretty sure there were no "detergent" motor oils back then,maybe no multi vis either(?).

You can find anything & everything about oil here;
http://www.bobistheoilguy.com/

If at all possable, drop the pan and clean. Detergent oil keeps dirt in suspension (so it can be removed by flow flow filter) where as non detergent oil allows dirt to drop out. Detergent oil does not "scrub or clean" the inside of an engine. Best is to clean the pan, replace, fill and run for a week or so and do it again. After enough cleaning so the pan stays clean, go ahead and use any modern oil.

Like CB says, probably any oil that was within reach has been used at one time in that truck. Detergent, non-detergent, single vis, multi-vis.
Cleaning the pan out is a great idea.
Companies like BG make oil system cleaners.
My experience with the BG product is that you don't want the first can of it to stay in more than a few minutes! It cleans that fast!
Good luck.

HMM? 1951, sitting since the late 1960's, that would be less than 20 years on the road. I suspect that very little "crud" would have been generated when the engine was out of service and just sitting for 43 or more years.
I'm wondering why the car Was parked.
If the car is strait as you say, this would make it a narrow body of water that connects two larger bodies of water, so I would check for rust.

A young country bumpkin is driving his Rambler along a country road and he has his GF in the front seat snuggling up next to him. After a time she asks if he might like to get into the back seat. he Replies, "NO, I would rather stay up here with you."

Two Nuns are on their way to town with the company Rambler. At the first traffic light a crazy guy jumps on the hood of the Rambler American and starts screaming his love for them and his need for some "special" personal attention. The Nun driving the Rambler tries to swerve left and right in rapid succession but the crazy guy continues to ride on the hood whilst holding onto the wipers. The riding Nun says, "For God's sake, turn on the wipers and break his grip!" The vacuum wipers did not work. The Nun at the wheel yells at her passenger and says, "Show him your cross!!" The passenger Nun rolls the window down a few centimeters and yells, " Get off of the f'n hood you SOB!"

My Dad told me that Rambler was the first company to offer a heated rear window on their cars. He said that they did this out of courtesy to their customers so the person pushing the car could keep their hands warm on a cold day.

Did you know that 75% of all Ramblers are on the road? The other 5% are in the shop. 20% would not start and are sitting in the garage.

I enjoyed that!

My first car was a '63 rambler classic.,,,no need to hop in the back seat,,they had nash seats..the front seatbacks laid down flush with the rear seat and you had a king size play zone...none of this nonsense of writhing around cramped in the rear seat..my second car was a '64 rambler American,,,

My brother used to collect motorcycles and he has had a few interesting cars.
Years ago, he had a beautiful 1957 Oldsmobile 98 with the J2 engine option. He offered it for sale and out of pity, he took a Rambler in on trade. The new owner had to pay more than twice the amount he got on trade-in. My brother had no intention of ever driving the Rambler so he advertised its destruction and sold tickets to the event. all of the money was given to a recognised charity. First, he had an engine blow-up where persons chose a time that they thought the engine would quit and he would give the winner a $100 of his own pocket. Tickets were $10 each. After the engine ran itself to destruction, with the throttle tied wide open, he offered three blows to the body of the car with a sledge hammer for $10 and the line formed on the right. The previous owner was out for a drive in his '57 Olds and happened by just as the Rambler spilled the contents of its engine. He was mortified and begged to have the carnage stopped. Monday morning came bright and early and the scrap truck arrived to take the carcass away for its final insult. My brother picked up the heavy tarp that was under the Rambler for its last hurrah and disposed of it properly.
My brother matched the amount of money raised and a good time was had by all who attended his little event in the country. He had a sign in his garage that suggested, "I HAVE NEVER SEEN A RAMBLER THAT I DIDN'T DISLIKE"