It's time to service the front and rear diffs in my Kia. The manual specifies SAE90 GL5 and Kia customer service confirmed that SAE90 straight weight is what I need to use to maintain warranty. I have located 3 gear lubes that are readily available that meet the spec. 1)Motul PA-90 2)Bel-ray Gear Saver SAE90 3)PJ1 hypoid gear oil. I also considered LE1604 but it is harder to find. What would you guys suggest?