I think that the SYNTHETIC GL-4&5 can meet both specs without the dreaded sulphur adds needed in a dino-based GL-5. Just a guess, but it makes sense. I have been sniffing them, all the GL-5 only dino and semi fluids smell greasy. GL-4&5 Syns smell like Tide. Costal Syn Blend smelled like Tide too, but weaker than the RP. My order of Motul got screwed up and I ended up with RP 75-90 Full Synth GL-4&5. List was $15, price was $9.50 and they guys gave me the curtosey discount, $22 for 3q was too good to turn down. In the Coupe GT it goes and if I like it I have .75q leftover toward filling my A4.