Subaru Outback, change the spark plugs?

My 2001 Outback has 125,000 miles with an 6 cylinder engine. It runs great but I am quite sure the plugs have never been changed. Do I need to? My favorite mechanic quoted me $250.00 for the job. What’s the upside? An increase of 2% gas mileage would take 10 years to recoup the expense.


They should have been changed about 60k miles back IMHO. The job could run considerably more than 250 bucks if those plugs are frozen in place now. Removal may possibly bring the threads out with the plugs.

One question: has the timing belt been changed? If not, you’re on borrowed time.

H6 = timing chain

Andrew is correct that the H6 engine uses a timing chain, rather than a belt. And as OK4450 stated, those spark plugs are long overdue for a change, as can be verified by looking at the manufacturer’s maintenance schedule that is sitting in the glove compartment. And, as OK said, leaving the plugs in for that long in an aluminum engine can result in damage to the threads when attempting to remove them from their frozen-in positions.

There really is a reason to follow the manufacturer’s maintenance recommendations, and that is to reduce your total maintenance and repair costs in the long run, while improving the longevity of the vehicle. Skipping vital maintenance is false economy.

The biggest issue is that your spark plugs are well beyond design life now and failure will likely happen. Ignoring maintenance for me is a recipie for being that car broken down. I believe AAA finds the largest amount of breakdowns are due to ignored preventative maintenance items.

$250 is well worth it instead of spending a few hours dealing with towing and finding a ride etc in my world.

Right on! Overheated engines/radiators are #1, broken fan belts, battery problems (no start), out of gas (believe it or not) round out the list. Failed transmissions have reared their ugly head in the last 15 years, while flat tires are not the problem they used to be due to better quality and longer life. The AAA constantly pushes maintenance, since most of their calls are preventable.