Most Common Major Oil Leak on Infiniti and Nissan V6 Engines So another common contention with these vehicles is you’ll take it to the dealership or other mechanics ; they’ll look at this oil leak and they will say it’s the oil pan ; that’s a very common misconception , now these do leak sometimes however ninety eight point nine nine nine percent of the time on the 3.5 liter Nissan / Infiniti engine they leak from the oil cooler seal ; there’s a six dollar oil seal back here ; it’s under high pressure and it gets old after time this car has well over a hundred thousand miles it just needs an oil cooler seal we’ll wash it and we’ll recheck it and see if it still needs an oil pan I’m willing to bet ninety-eight percent of this oil is just from this oil cooler seal back here not the oil filter , the oil cooler seal.