Regarding leaks. Synthetic has smaller molecules or something like that, so it is more likely to leak through a weak seal than conventional. So if you didnt have any leaks you shouldn't have any now unless any seals are just barely holding up. The notion that synthetic causes leaks isnt true.

88 Montero, StarQuest turbo, Kormex 5speed +tuff-pan w/phoenix f. stage2 clutch, 4in lift+33' tires, 4.875 lsd, short-throw shifter, Aisin hubs, SR big brakes, gen2 uca's, elantra alt, and so much more... 16g turbo w/hardpipes + 4.90 locking disk-brake axle soon (maybe lsd or aussie front??)