2010 Cadillac CTS V6, 36,600 miles. 13 months and 870 miles since last oil change at dealer with full synthetic Dexos. OLM says 92% left. I usually drive it long enough to warm up oil--few, if any, short trips in four-season midwest. Going on a 3,000 mile road trip. Would like to wait until I return to get oil changed. Recommendations? Thanks.