Mobil 1 in the SR
What ever is on sale for the Ford.
I run Canola. Runs a lot cleaner than Sunflower Oil.
Royal Purple!
on my KA, & will continue on my CA 
100% Synthetic, no problems.
Mobil1 10w30
elf evolution 5w30
I hate to break it to you but Castrol Syntec, although being advertised as a full synthetic is actually a semi synthetic. It is essentially a base stock oil that is massaged into a synthetic like many other synthetics now. MOST major oil companies do this. Mobil1 actually sued Castrol over this but eventually lost the battle as the courts decided the end product could be classified as synthetic even though it wasn’t 100% synthetic.
That’s why sticking to brands like Royal Purple, Motul & Redline guarantee you that you are getting a true full synthetic.
NISMO_GTR - what viscosity of ENEOS oil are you using? I have some 0w-50 oil that I had sent to me but Im VERY concerned about running it in a street car but have been told it will be safe.
Royal Purple 5W20 in the Z
Amsoil 0-30w, 5-30w, 10-30w are all good and can go 40k or 1 year drain interval with a Amsoil EA oil filter.
Also…
Mobile 1 has a TBD (Total Base Number) of 8.45 as Amsoil has a TBN of 12.35… The higher the TBN the longer your oil will stay in grade.