I don't know about your leaking issues and what not but i used to use GTX 5-30 in my 1995 SHO with 131k on it. Car was a rocket! Switched to 5-30 Mobil one and the Engine almost instantly like 4 miles down the road started with a ticking noise. 24 miles later BLEW up.. Spun bearing cuased the #6 piston to stop rotating and in turn shattered the connecting rod. Could mobil one be the cuase sure i guess or it could have been that the Car would Rev to like 8300rpm everyday. Could be a wierd coincidence.
I used mobil one the whole life of My CSVT and noticed one difference.. GTX temp would be higher than with the Mobil 1.
Ok Tenzo 4 life!
