Over a year ago, at about 58,000 miles on the odometer, my 2003 4-cyl. Toyota Highlander had burned through virtually all its oil 6,500 miles after the previous oil change. After a year of observation and 3,000-mile oil change intervals (during which it loses about 1.5 quarts), the dealer diagnosed the problem as a valve seal leak: He said I'd need to replace the engine rings, resurface the valves, and replace the valve seals -- at a total cost of nearly $2,300 including tax. Here's the question: What if I just keep replacing the oil every 3,000 miles instead of doing the repair? Would there be any more damage as a result, or would things stay pretty much the same? I'd much rather spend a little under $150 a year on oil changes for a few more years than blow $2,300 on it!
P.S.: For those aware of Toyota's sludging problems, that was considered as a probable cause of the oil-buring problem. But the inspection revealed only very slight gelling, according to the dealer.