quote:Again, don't sell Valvoline oils short. Their oils are very competitive in price and performance.
What you need to know about motor oil -- Do not be alarmed when motor oil turns black, which can happen long before the oil's protection value is used up. Engine combustion produces soot, and other byproducts disperse throughout the oil, turning it dark. But if the oil is thick and dark, that means its contaminant-dispersant qualities have diminished and that it should be changed. -- You can mix most synthetic oils with conventional motor oils inasmuch as both currently are derived from crude oil-based fluids. But be careful with new-generation synthetics that could contain non-crude-derived chemicals. -- High-mileage oils generally contain either more or higher-quality seal conditioners to help protect valve seals in older cars -- typically those five years old, or with 75,000 miles of use. A side bar article from the Detroit Daily Press about Valvoline. -- Daily commuting constitutes severe, stop-and-go driving, short trips and lengthy idling, all of which put extra strain on your engine. Regular long-distance highway driving is easier on most engines, thanks to better combustion of fuels and constant engine cooling in steady travel. Change oil more frequently for severe driving. Change it less frequently if most of your driving is on the highway. Consult your owner's manual for recommended oil change intervals.