Does anyone have any input on Valvoline Durablend 85-140 gear oil? I've been running it in the Jeep for $5.49 a quart. I figure when I go wheelin' I risk contamination from water, so I don't want to spend a lot on gear oil. Durablend is about half the money compared to full synthetics. I change it about 2 times a year. (when it looks like it needs it) Just wanted to see if it's a good oil.