Time for an oil change.
I've been running Castrol GTX 20w50.
I know how oil debates can get, sorry.
Is there something better, with more ZDP or whatever our old engines like?
I searched a bit but nothing "definitive" jumped out at me.

If the ZDDP is what you're worried about, Castrol Syntec 20W-50 claims to be up to the job. Moss also carries some collector car oil that has it, but both of those are on the expensive side. I use Valvoline VR-1 racing oil, which is readily available, costs less than the Syntec, and has good ZDDP levels. It's fine for street use too. Good detergent additives too, it actually cleaned up some sludge that was around the rockers.

Maybe Hap will chime in with his wisdom, but as I recall the ZDDP issue was more of an issue for newly rebuilt engines, whereas engines that are already well broken in aren't really in trouble using garden variety 20W-50. Still, I'll stick to the Valvoline or Syntec, or get an additive that has ZDDP in it.

I use 4 stroke motorcycle oil - inexpensive and available

Just got back from parts run and picked up the VR1 Valvoline as referenced in other threads. I sure don't want very expensive oil, as too much ends up on the ground!

The type and what ingredients are desired seem to be a matter of choice based on opinions of others, personal comfort, what grandpa used, and a smattering of research.

I tend to not mention the brand I use or proclaim the great and wonderful qualities it possesses. Because in the end it is only my opinion.

What I usually offer as a suggestion is to research information from companies that have a vested interest in component longevity, some that make cams for instance, to figure out the properties you would like in the oil you use.

And armed with that information then contact companies that produce oil and ask them what they with those characteristics. When I chose my oil I talked to engineers at a few companies until I was satisfied.

Why do I say this and why do I not just tell you what I use? Simple, I pay the bills for my car and you pay the bills for your car. I don't want responsibility for yours and you should not just accept my judgment. That is not meant to be mean and sarcastic, it is just that I think it is too important to accept anecdotal information.

And finally, please remember this is only my opinion.

here is some info on the web that I found in my research on the same issue

www.macysgarage.com/myweb6/ZDDP.htm
www.svmgcc.org/tech_tips/oil_is_killing.htm
www.foreignpartspositively.com/ArticleIndex.htm

If all you want in it is ZDDP a big jug of diesel engine oil will do the trick.
Tractor oil, that kind of thing.

I also like the VR-1.

My Sprite is generously marking its territory too, I think the inspection cover gaskets need some attention as they tend to dry out when a car sits for years.

In the end it's best to change the oil regularly and often IMHO.

So, what you're saying is pour it in the top and run it out the bottom? I must be doing it right then

Yes, constant loss system, no need for oil change that way, very forward thinking of them, also cuts down the dust on the road.

I remember when we had gravel ally ways between the rows of houses in our town. It was considered being a good neighbor to dump the waste oil when changing oil on the gravel to keep down the dust. Of course that was 50+ years ago.

Watching one of the British TV car shows the other night they had a segment on the Abingdon Car Show.

In it was a very early MG that had built in a 1 gallon oil reserve tank.
You poured oil in at the top on the engine side of the firewall and then to apply oil to the engine you turned a valve in the cockpit.

Ingenious Engineering on their part! Wish my car had that!!

Passive undercarriage rust prevention.

two interesting articles on the use of ZDDP. both are NOT in support of the need for older cars. one of the articles is from a GM engineer.

http://www.nonlintec.com/sprite/oils_and_zddp.pdf
http://www.nonlintec.com/sprite/oil_myths.pdf

I use Vavoline VR1, it's fairly cheap, easy to find, I've used in my race cars for 20+ years, it a-ok for street use and it has 1200 ppm ZDDP. Alot of folks including myself, don't think you need ZDDP counts of 1200ppm (all oil has some, the goverment just reduced it in most oils to a lower count) for nothing more than cam break in on new engine, but I still use VR1, because I always used VR1. The bigger issue in my opinion, is getting lifter and camshaft that are properly hardened, they's alot of sub par stuff being sold to us in this regard, and you better believe ZDDP will be a scapegoat for this in the future, I already seen one engine builder blamme oil and zddp for a turned bearing, sorry I ain't buying that.

If the underside of your car doesn't look like the underside of a B-17's wings with the oil streaks, either your car is out of oil or it's not British :

By the way, I've been running 5W-50 Syntec in mine...never have been able to find 20W-50 here. Too thin at the low end?

come on, really?

Yeah, I've heard of people doing this, too. It was a different world back then.

Dad used to poor it along the base of the slab for termites and in the ditch in front of the house. When it rained, there was an oil slick two blocks long down the ditch. He did it to keep the grass in the ditch down. The neighbor directly next door would get so mad. He hasn't done it in 20 years or so. There is a snapping turtle that lives in the culvert under our driveway right where he poured it in. He's been there forever. He hasn't gotten any bigger, but he's still alive and doesn't have three heads.

Waste oil on dirt roads? The original blacktop. I've been watching our new highway project outside my window for months. Gotta love the smell of hot tar.

Guess I should be watching out for weird looking turtles...