07 Road King with 24,000 miles and I've always used Castrol 20/50 until today. Went to O'Reilly's to buy my Castrol and noticed something I haven't seen before Castrol Syn Blend? I have never been sold on straight synthetic since I change my oil every 2,500 miles and don't believe I get that much added protection for three times the cost, again, especially if I change oil every 2,500 miles. However, the Syn Blend (part synthetic) was 5.99 a quart vs. 4.99 for regular Castrol 20/50. Bottom line I bought it and my question is "has anyone tried this product or have any comments regarding a product that is part synthetic"?