can I switch back to conventional oil?Car not driven just idle
Exactly what oil is in the car?
My Brad Penn (now Penn Grade) oil is a semi-synthetic with a high amount of zinc and phosphorus.
IMHO and based on reading a bit on the subject....
First, a lot of the oils aimed at the old car, flat tappet market are synthetic or semi-synthetic. Some are conventional oil too.
Second, most of the damage that occurs from using an oil with lower ZDDP levels are where there's high pressure valve springs. Your Chrysler has lower pressure springs that are 46 years old.
Third, yes you do need some ZDDP with your flat tappet cam, but damage doesn't just happen the second you fire up your engine... It takes a bunch of miles and read my second point.
So... First thing is to fix your leaks. Doesn't matter what oil you put in, it's still gonna leak. Valve covers are easy...
If you feel more comfortable, change the oil. You haven't done any damage and I'd say if you ran the oil until the next change, it will be OK. But... Since you are questioning it, go ahead and change the oil. I run the Brad Penn oil
Motor Oil | Brad Penn | PennGrade 1® High Performance Motor Oil There are a lot of other, similar oils and if you ask 10 guys what they run, they will give 10 answers.
But, again, what oil did you use?