I'm trying to find the right oil for the outdrive on the boat it's a Glastron 195 sx 5.0 volvo penta with a volvo sx drive but my nearest volvo marine shop is 2 hrs away, I have walmart & autozone, what can I use for 75w-90 full synthetic gear oil, I've found valvoline but they all say limited slip and for conventional use. What can I use that can be found at walmart or autozone? That isn't so pricey either, thank you