Motor oil, car engine improvements combine to extend intervals between oil changes

GM, Honda, others use indicator lights to tell motorists when to change oil

Chrysler moving to indicator lights in 2008 models

Ford lengthened recommended oil change interval for 2008 models to 7.5K miles

VW upped oil-change recommendation to 10K miles on 2007 gasoline-powered models

BMW's synthetic oil lasts up to 15K miles if car's oil monitor agrees

Median age of cars last year was record 9.2 years, up from 8.1 years in 1997

Reduced need for oil changes, engine tuneups saves $600 over 5 years

Drivers may fall under shorter interval of "severe driving schedule"

Includes stop-and-go, hot weather, heavy-load driving

Oil change indicator lights designed to take higher-demand driving into account

"It's dangerous and wasteful to prescribe an oil drain interval. You'll change it too early or too late." -- Charlie Freese, engineer, GM

Shell Lubricants owns Quaker State, Pennzoil oil brands

Operates Jiffy Lube oil-change chain

Long ago abandoned corporatewide 3K mile oil-change message