Sorry if this question was already addressed by members, but I just wanted your feedback.Presently, I am using Castrol GTX 10w30 in both of my vehicles(1995 Nissan Truck 4x4 V6 66000 miles/1998 Infinity QX4 45000 miles). I always change the oil and filter in both every 3 months or 3000 miles without fail, the 3 month period always comes before the 3000 miles. I was thinking about switching to the Wal-mart Super Tech Synthetic 5w30 winter time and 10w30 warm weather.Is this a good choice? Is this good oil? Thanks in advance for your feedback.