TWO WEEKS AFTER ADDING 1/2 A QUART OF LUCAS HEAVY DUTY GEAR OIL TO THE G35 MANUAL TRANSMISSION I WROTE TO LUCAS OIL CO ABOUT IT.THE RESPONSE WAS VERY UNCLEAR.THE REP SAID THAT LUCAS HEAVY DUTY DOES CONTAIN CORROSIVE ADDITIVES HARMFULL TO THE SYNCHROS, BUT WAS NOT ABLE TO TELL IF 1/2 A QUART ADDED TO THE ALREADY 3 QUARTS OF REGULAR TRANSMISSION OIL, IS TO MUCH OR TO LITTLE TO CAUSE ANY DAMAGE.HE STATED THAT ANY TRANSMISSION OIL DOES HAVE A SMALL AMOUNT OF CORROSIVE ADDITIVES LIKE SULPHUR.HE PROMISED TO INVESTIGATE AND CALL BACK. WHEN HE DOES I WILL POST THE ANSWER HERE.

Welcome to NICO!

Thanks for the info! Please watch your CAPS...it can be distracting to readers or come off as yelling.

I would recommend to use Nissan gear oil only...

I've also been curious about gear oil alternatives. Are there suitable synthetics? would that matter?

With the transmission and differential, I'd be careful. If you have a failure, and didn't use the proper additives, the warranty will not cover the damage.