FWIW, back in the day, using a number of 0W20 oils,
including,TGMO, MGMO, Sustina, and RL,
the BEST mpg I got was with RL !
HTHS 2.9
VI 172
The others were barely
HTHS 2.6
VI ~ 220 and higher
I always attributed this to the huge amount of moly in RL.
Also, Dave has stated that RL is a great oil vs LSPI, in spite of the high calcium.