Ford 400m oil suggestions

Aug 2, 2018
South Carolina
So my 75 LTD is coming up for a oil change, and was wondering what yall would suggest. Completely stock engine with 40k original miles. I know the inherent problems of these engines and from what I read they favor thicker oil. Right now I have hdeo 10w30 duragard ck4. Around 1200 zink 1100 phosphorous according to there spec sheet. I plan on installing a oil and temp guage. All dummy lights now which did come on at a drive through once but temp and oil combined to just one engine light. I believe it was temp related cause I had a Windsor thermostat in a Cleveland block. There is a difference. So what yall got?
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After I had the cats removed and smog pump deleted, I added true dual 2.25 exhaust with thrush mufflers, it feels like a whole new car.
Ok. Synthetic or conventional, your choice. The engine came off the assembly line with 10w-30. ANY brand of 10w-30 now is light years better than what was available in 1975. Hard to find a bad oil today. Personally? I would use SuperTech Synthetic 10w-30. Why? Cheap, available and adequate. High Zn is not required, even back then. 600ppm is all that is required for stock engines and most oils are far above that. If the main seals are SEEPING (not blowing oil), try a HM oil. For engine cleaning I recommend Mobil1 HM 10w-30. Others say Pennzoil is also good but I have no experience with it.
You say it's stock, so change the timing chain to an aftermarket set that doesn't retard the timing. It's not that big of a job. You'll want the plastic camshaft gear out of there anyways. Those plastic camshaft gears usually fail way before 100K miles.
I plan on doing that aswell. The engine has 40k original miles but still has 45 years of age. I might install a new RV cam aswell. Another one of my cars is getting a new chain cause I hear it slapping. A 1984 chrysler fifth avenue with a LA 318.
10w30 Full synth, with a Zinc add in from a brand of your choice. Did this in a few engines and put them to work in the upper RPM range. No issues what so ever.