Cobra 53
Now you have the dipstick "calibrated"...bet a lot of these cars do not have one...!
Do you know what type CAM SHAFT your engine has?
If it's a hydraulic ROLLER cam you can probably safely use a "modern"
oil like the Castrol EDGE FST 10w/60 you are running.
If it's a FLAT TAPPET cam...whether hydraulic or solid lifter consider adding ZDDP. There are additives that will do it or better, use one of the "old" formula oils that include ZDDP. There are several brands, Brad Penn comes to mind.
The lobes on a flat tappet camshaft will probably erode without a high pressure additive...specifically ZDDP.
(Roller-cam engines don't really need it).
Look up ZDDP. It is a anti-scuff, high-pressure additive for engines that have the flat tappet cam. ISKY, COMP CAMS and others have additives you
OK, how you would determine the lifter type without pulling the intake manifold I do know...! in which case running a ZDDP additive would be good insurance.
Pete
Must be several threads that deal with lack of ZDDP and destroyed flat tapped cams.