full groove main bearings oil pressure ?

For me, any pressure below 20-psi is 'worrying'.

The cambearings could still be the cause of the low hot oil pressure.
More oil volume could help keeping the pressure up a bit.

Or change to a 10w40 oil perhaps.

I agree ..under 20 is scary. I will probably put in a HV pump. I guess I could even go 20W50.