I tow a pretty heavy travel trailer and a 21 foot boat. Since 2005 I have always used Mobil 1 75/140 rear and 75-90 front. If you tow I would also change transfer case oil frequently as well. I have always used Mobil 1 ATF in that. In the trans I use J/S-Matic. Good Luck.
2005 SE Off Road: JBA LT Silver ceramic coated headers, Cajun B-Pipes with Heavy Metal Cats, Borla Dual SS Cat Back, Uprev Tuned, K&N Air Charger, CSF 3328 Aluminum Radiator, Grille Craft Upper and Lower Grill, Burtman Rear Air Reflector, Manik SS Nerf Bars, Nissan Tow Mirrors, Bilstein HD's, Moog 81085 Rear Coils, AirLift 1000 Rear Springs.