We Ran the 2.7 EcoBoost & 3.5 EcoBoost Side by Side for 250,000 Miles — A Clear Winner

We bought two identical Ford F-150 crew cabs on the same day from the same dealer with the same trim level. The only difference was under the hood. One got the 2.7 EcoBoost, the other got the 3.5 EcoBoost. Then we drove them exactly the same way on the same routes with the same loads for 250,000 miles and wrote down every single repair. I've been a Ford technician for over 15 years and I've heard the 2.7 versus 3.5 debate more times than I can count. Everybody has an opinion. Almost nobody has data. So we decided to generate our own. What we found surprised even me. And by the time we hit 200,000 miles, one of these engines had pulled so far ahead that the comparison almost wasn't fair anymore. Here's exactly what happened mile by mile. Let's start with what these two engines actually are because the differences run a lot deeper than displacement. The 2.7 EcoBoost is a twin turbocharged V6 that Ford introduced in 2015. It uses a compacted graphite iron block, which is the same material family used in heavy-duty diesel engines because of how well it resists cracking under high cylinder pressure. That's an unusual choice for a gasoline V6 and it's one of the reasons the 2.7 has earned such a strong reliability reputation despite being the smaller of the two engines. The 3.5 EcoBoost, on the other hand, uses a more conventional aluminum block. It's larger, it produces more torque, and it's rated to tow significantly more weight. On paper, the 3.5 looks like the stronger engine in almost every category. Horsepower, torque, and towing capacity all favor the bigger motor. But raw output numbers don't tell you what happens to an engine after 10 years and a quarter million miles of real use. And that's exactly the gap our test was designed to fill. Both trucks left the dealership with the same 10-speed automatic transmission, the same 3.55 rear axle ratio, and the same tow package. We alternated drivers weekly so no single driving style could skew the results. And both trucks pulled the same enclosed trailer on hauling days, loaded to roughly 6,000 pounds, which sits comfortably within the capacity of both engines. We changed the oil at the same intervals using the same synthetic 5W-30, rotated tires together, and logged every dashboard warning, every unusual noise, and every shop visit in a shared spreadsheet. If something broke, we didn't guess why. We pulled the part, inspected it, and in several cases, sent it out for analysis. This wasn't a casual comparison. It was closer to a fleet reliability study, just run on two trucks instead of 200. We also made a point of splitting the driving evenly between highway commuting, stop-and-go city traffic, and dedicated towing days, roughly in a 60-30-10 split, because engines don't wear the same way under every condition. A truck that only ever cruises the interstate tells you almost nothing about how it handles heat cycling and traffic, and a truck that only tows tells you nothing about everyday drivability. We wanted a realistic ownership picture, the kind that actually matches how most F-150 owners use their trucks, which, according to Ford's own market research, skews heavily toward commuting and occasional hauling rather than constant maximum-capacity towing. That distinction turned out to matter more than we expected once the higher mileage numbers started coming in. The first 50,000 miles were almost boring. Both engines ran clean. Fuel economy on the 2.7 truck consistently landed in the low 20s on the highway, while the 3.5 truck settled in a few miles per gallon lower, which lines up with what Ford's own EPA ratings and years of owner-reported data have shown for these two engines. That gap held steady through city driving, too. The 2.7's smaller displacement and lighter overall weight meant less fuel burned just moving the truck itself. Even before you factor in load, towing changed the picture somewhat. The 3.5 truck pulled the trailer with noticeably less turbo lag and less need to downshift on grades since it simply has more torque available lower in the RPM range. The 2.7 could still tow the same load without issue, but the turbos worked harder to do it, spooling more aggressively and holding boost longer on sustained climbs. Neither truck struggled, but you could feel the difference in how each engine approached the same job. Somewhere around mile 60,000, the first real issue showed up, and it was on the 3.5 truck. We started noticing a faint rattle on cold starts, the kind that clears up after a few seconds once oil pressure builds. If you've spent any time in Ford truck forums, you already know where this is going. That rattle is the calling card of cam phaser wear, and it's one of the most well-documented issues on the 3.5 EcoBoost, particularly on the first-generation engines built before Ford revised the design. Cam phasers control variable valve timing by using oil pressure to rotate the camshaft relative to the timing sprocket. When that system starts to wear, you get exactly the kind of rattle we heard, especially on startup when oil pressure hasn't built up yet. We pulled the covers and confirmed it. The phasers weren't destroyed, but wear was clearly present at just 60,000 miles. Ford addressed this issue in later production years by revising the phaser design and improving oil delivery to that area, and trucks built after that update do show meaningfully fewer complaints. Our test truck, unfortunately, was built before some of those revisions were fully baked in, so we got a front-row seat to the exact failure mode this engine has become known for. The 2.7 truck, meanwhile, hit 60,000 miles with nothing to report beyond routine maintenance. No rattles, no warning lights, no unusual oil consumption. That's not luck. The 2.7's compacted graphite iron block and its overall engineering focus on durability over outright output was a deliberate design choice by Ford, and it shows in exactly this kind of long-haul comparison. The engine simply has fewer stress points working against it at a given mileage because it isn't being asked to produce the same peak torque numbers as the 3.5. Turbo behavior was another area where the two engines quietly diverged well before any hard failures showed up. The 3.5's twin turbos are larger and built to support significantly more airflow, which is exactly what lets it produce that low-end torque advantage when towing. But larger turbos also mean more rotating mass spinning at extreme speeds, more heat soak after a hard pull, and more reliance on proper cool-down before shutdown. We made sure both trucks got a short idle period after heavy towing before shutting off, which protects turbo bearings on any EcoBoost engine. But the 3.5's turbos were simply working harder more often given the loads we were asking of it. The 2.7's smaller turbos, by comparison, rarely felt stressed even under moderate towing, spinning up quickly, but never feeling like they were near their ceiling during our test. By mile 100,000, the gap started to widen further. We addressed the cam phaser wear on the 3.5 with an oil system flush and close monitoring rather than a full replacement, since the wear hadn't progressed to the point of triggering codes yet. But we also started seeing something else on the 3.5 truck, mild coolant loss that we eventually traced to a degraded plastic coolant expansion tank fitting. This is a known weak point on higher mileage EcoBoost VI6 engines in general, not exclusive to the 3.5, but the added heat load from towing more frequently on the bigger engine seemed to accelerate it. We replaced the tank, and it held up for the rest of the test. Around this same mileage, both trucks needed spark plug replacements, which is standard maintenance on these engines, and nothing either truck could avoid. The 2.7 crossed 100,000 miles with a single unscheduled repair, a leaking oil pan gasket. This is actually a well-known issue specifically on early production 2.7 EcoBoost engines, generally built before 2018, where the gasket material didn't hold up as well as Ford intended. It's such a common failure that most of these gaskets on the road today have already been replaced under warranty or by an independent shop, and ours was no exception. Once replaced with a revised gasket, the issue never returned. Outside of that single repair, the maintenance log for the 2.7 truck through 100,000 miles read almost exactly like the factory schedule. Oil changes, air filters, one set of brake pads, and nothing else. It's worth pausing here to talk about towing capacity because it's the number most buyers fixate on when choosing between these two engines, and our test data adds some useful context to it. The 3.5 is rated to tow up to roughly 12,000 pounds depending on configuration, while the 2.7 typically tops out closer to 7,000 to 8,500 pounds depending on cab and bed configuration. That's a real meaningful gap if you regularly haul a large travel trailer or heavy equipment, but our 6,000-pound test load sat well within both engines' comfortable operating range, and that's actually where most F-150 owners live. Very few owners regularly tow anywhere near the maximum rated capacity of either engine, and when you're operating well under an engine's ceiling, the smaller engine isn't working any harder relative to its own limits than the bigger one is. That's part of why the 2.7 held up so well in our test despite towing on a regular schedule. It was never actually being pushed anywhere close to its rated maximum, so it never had to work outside the range it was engineered around. Between 100,000 and 150,000 miles, we started to see the story crystallize. Both direct-injection EcoBoost engines are known for carbon buildup on the intake valves since direct-injection sprays fuel straight into the combustion chamber instead of over the valves, which means there's nothing washing away the oil vapor and blow-by residue that naturally accumulates there over time. This is a shared weakness of both engines, not something unique to either one, and we saw it show up on both trucks in the form of a slightly rougher, idle, and marginally reduced throttle response. We addressed it with a walnut shell media induction service on both trucks around the 130,000 mile mark, which restored smooth idle and responsiveness on both. It's worth noting that Ford's second generation 3.5 EcoBoost, introduced for the 2017 model year, added a secondary port injection system specifically to reduce this kind of carbon buildup by keeping some fuel spraying over the valves the traditional way. Our test truck predated that update, so it dealt with the full brunt of direct-injection-only carbon accumulation, while newer 3.5 EcoBoost owners running the dual-injection setup report noticeably less of this issue. The 3.5 truck's second major repair came at around 145,000 miles when the cam phaser rattle we'd been monitoring finally progressed to the point of throwing a code and requiring an actual timing chain and phaser service. This is not a small job. It involves the front timing cover, the chains, the guides, and both phasers, and on a customer vehicle, this repair commonly runs into several thousand dollars depending on the shop and the extent of the wear found once everything is opened up. We did the work ourselves, documented every worn component, and confirmed that the guides and chain had stretched enough to justify full replacement rather than a partial fix. After the repair, the engine ran smooth and quiet again, but it was a serious dent in the reliability story for that truck, and it happened well before the halfway point of our planned 250,000-mile test. The 2.7 truck's next real issue didn't show up until almost 170,000 miles, and even then, it was minor, a failed ignition coil, which is about as routine a wear item as a modern turbocharged engine can throw at you. We replaced it in under an hour and moved on. Fuel economy on the 2.7 remained remarkably consistent throughout this stretch, holding within a mile or two per gallon of where it started back at delivery. The 3.5 truck's fuel economy had drifted down slightly since the timing chain service, likely due to the induction service timing and some residual carbon that even the walnut blasting didn't fully clear, though it stayed within a normal range for the engine. From 170,000 to 220,000 miles, both trucks kept working, but the character of their maintenance logs had become very different. The 2.7 truck's file was thin, oil changes, two sets of brake pads across the whole test, a battery replacement, and the ignition coil. The 3.5 truck's file was considerably thicker, the cam phaser and timing chain job, the coolant tank, an alternator replacement at around 190,000 miles, and a water pump that started weeping coolant right around 210,000 miles and needed replacement. Water pump failures on these engines aren't unheard of at higher mileage since the pump is driven off the timing system and takes on extra heat and stress under towing loads, which our 3.5 truck saw more of thanks to its higher rated capacity, encouraging us to load it more aggressively during the hauling phases of the test. We also tracked transmission behavior closely throughout the test since both trucks shared the same 10-speed automatic and any differences there would point to something happening on the engine side rather than the transmission itself. Both transmissions performed almost identically through 250,000 miles with normal fluid services at the recommended intervals and no unscheduled repairs on either truck. That consistency actually strengthens the engine comparison because it rules out the transmission as a variable and confirms that the gap we saw in total repair costs and labor hours came specifically from how each engine aged, not from some unrelated drivetrain difference between the two trucks. We hit 250,000 miles on both trucks within about three weeks of each other and when we sat down to tally the final numbers, the picture was clear even though neither engine had actually failed outright. The 2.7 EcoBoost completed the full 250,000 mile test on essentially its original internals. No timing component replacement, no major cooling system failure and total unscheduled repair costs that stayed well under $2,000 across the entire test, almost all of it from that early oil pan gasket in the ignition coil. Fuel economy stayed remarkably stable from delivery to the finish line. The 3.5 EcoBoost, meanwhile, needed a full timing chain and cam phaser service, a coolant expansion tank, an alternator and a water pump with total unscheduled repair costs landing several times higher than the 2.7s over the same distance. It also required noticeably more labor hours overall since jobs like the timing chain service on this engine are inherently more involved than anything the 2.7 needed. None of this means the 3.5 EcoBoost is a bad engine. It genuinely towed heavier loads with less strain, produced more usable power under load and every failure we documented is a known well-understood issue with an established repair path. Several of which Ford has already improved in later production years through revised phasers and the added port injection system on the second-generation engine. If your truck spends most of its life towing at or near its rated capacity, that extra torque and capability from the 3.5 is worth something real and a well-maintained second-generation 3.5 built after 2017 should reasonably be expected to hold up better than our earlier test engine did. But if your driving looks more like ours outside of the dedicated towing days, mostly commuting, occasional hauling well under the truck's maximum rating and a priority on minimizing trips to the shop over a long ownership period, the data from our 250,000 mile test points in one clear direction. The 2.7 EcoBoost with its compacted graphite iron block and lighter overall stress load simply asked less of itself to do the same job and over a quarter million miles, that difference in engineering philosophy showed up exactly where you'd expect it to in the repair log. One more thing worth mentioning before we wrap up. Resale value followed a similar pattern to what we saw in the repair logs. When we had both trucks independently appraised at the end of the test, the 2.7 truck came back with a slightly higher valuation relative to its original price, even accounting for its lower towing rating, largely because appraisers and used truck buyers alike have caught on to its reputation for lower long-term repair costs. That's not a huge factor for most people cross-shopping a new truck, but if you're thinking about total cost of ownership rather than just the sticker price and the payload numbers, it's one more data point worth factoring in alongside everything else we found. If you're cross-shopping these two trucks right now, don't just look at the horsepower and torque numbers on the window sticker. Think honestly about what you actually haul and how often you actually haul it because that answer should drive your engine choice more than the spec sheet does. And if you already own one of these trucks, the maintenance lessons from our test apply either way. Stay ahead of oil changes, don't ignore a cold start rattle if you're in a 3.5, and budget for an induction service somewhere in the 100,000 to 130,000 mile range, regardless of which engine you have, since carbon buildup is a shared reality of direct injection that neither engine fully escapes. If you found this comparison useful, subscribe for more real-world testing like this, and let me know in the comments which engine you're running and how many miles you've put on it. We're planning a follow-up test on the second generation 3.5 with the added port injection system to see how much of this gap closes on the updated engine, so stick around for that one. Thanks for watching, and I'll see you in the next video.