Valvoline VR-1 vs. Lucas Hot Rod oil

66
take 40 weigt oil all warmed up
a 10 40 oil the W spec is about the same at 0 degrees and a 5W or 0W
The thin at o degrees w0 oil just does not thin out with heat
a o w oil flows better no matter what your starting outside temp is
but it is the same all the same warmed up
the modern ois do not have or have much less friction modifers