Do V8s Require More Maintenance Than V6s?

In today's era of engine downsizing, forced induction, and hybridization, sheer engine size and displacement no longer guarantee superior power. Modern turbocharged V6s can often match — or even exceed — turbocharged V8s. Still, a V8 carries two more cylinders than to a V6, and that extra hardware brings its own set of considerations, as well as making a V6 engine sound different from a V8.

So do V8 engines require more maintenance than their V6 counterparts?  A V8 can cost more to maintain simply because it has more components, but the difference isn't huge, and it depends on more factors than just size and displacement. V8 engines typically require two more spark plugs, two more fuel injectors, more valves, and more oil during oil changes.

A V6 engine is also typically lighter and smaller, which can lower the strain on the engine mounts and associated components. This all translates to a V8 engine having a higher level of mechanical complexity, but the maintenance differences are typically insignificant. All engines need maintenance, and the number of cylinders is ultimately just one piece of a much larger puzzle.

For oil changes, BMW's N63B44 V8 engine, found in numerous BMW models, typically requires about 9 quarts (8.5 liters) of engine oil. The BMW B58B30M1 V6 engine is comparably smaller, and thus its oil capacity is rated at 6.5 quarts (6.2 liters). A survey carried out by AAA found that five quarts of full synthetic oil cost about $45 on average, or roughly $9 a quart. Assuming oil is changed twice a year, or sooner if the recommended mileage is exceeded, over five years, you could save roughly $225 by rocking a BMW V6 instead of a V8.

With two more cylinders, a V8 will require eight spark plugs, while a V6 requires six. As a general rule, you should change your spark plugs every 80,000 to 100,000 miles. AAA has also reported that, on average, a spark plug costs $5 to $25. This means that your BMW N63 V8 is going to cost you $10 to $50 more than the BMW B58 V6 because it has two additional spark plugs, and that's every 80,000 to 100,000 miles. 

Every engine is also going to require a coolant flush at some point. KBB recommends doings so every two years (30,000 miles). If we take our N63 and B58 examples, the former has a coolant capacity of 13.2 quarts (12.5 liters), while the latter is at 11 quarts (10.5 liters). If we do the math and take $8.30 to $10.30 as the average for a quart of coolant, it comes to about a difference of $18 to $23 per flush, or $37 to $45 over two flushes in four years. In the grand scheme of car costs, not that big of a difference.

You'd be forgiven for thinking that a Ford Coyote V8 costs more to repair and maintain than a 3.5-liter EcoBoost V6. However, over on the F150 Forum, owners discussed real-world costs of V8 and EcoBoost F150s, and many agreed the V8 is likely cheaper to maintain. User bylons808 summed it up: "The V8 will most likely be the lower maintenance engine in the long run. Anybody who has had a vehicle with turbos can tell you that."

Engine Crux, a site specializing in engine reliability and maintenance analysis, paints a similar picture, writing that maintenance and repair costs for the Coyote V8 are $100 to $200 cheaper than for EcoBoost V6 engines. The Coyote is a naturally aspirated engine, and it's simpler than a turbocharged EcoBoost engine, which can lead to lower costs. However, since V8s are larger, heavier, and often use beefier parts, it can cost more money to fix a V8 than a V6.

For more comprehensive repairs, such as an engine rebuild, you're also likely to pay more for a V8 than a V6. If the V8 engine is turbocharged, high-performance, and from an exotic automaker such as Ferrari, costs of repair can be excruciatingly expensive. Forced induction can raise temperatures, which may increase the likelihood of issues, but, once again, it's just one factor at play. Many turbocharged engines are highly reliable when well-designed and properly maintained.