I have a 2018 Subaru Forester with the 2.5l engine.I'm going to let the dealer do it's first oil change at 6k(factory)and then I'll do the others at every 6k with Valvoline Advanced Synthetic with only Subaru filters.No highway/no cruise/keep rod below 3k and it should last.
2019 Subaru Legacy 2.5L break-in Strategy
- Thread starter Patrick0525
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My wife just got a new 2018 Forester. During break-in you want (1) several heat cycles before you stress parts (2) high cylinder pressures to force the rings to seat against the cylinder wall (3) keep it cool so it doesn't glaze. One way to achieve all goals is take it easy for the first 50 miles, drive with varying speed and RPM, let it get to full temperature, then fully cool off to ambient, several times. Then smooth progressive brisk 75% to 100% throttle acceleration, brief to prevent heat build-up, followed by easy high speed cruise for max airflow to dissipate that heat, downshifts for engine braking to reverse pressures, and constantly vary the engine RPM and speed, don't use cruise control.
Note: New Lycoming & Continental piston aircraft engines require operation at 75% or greater power during the first 50 hours for break-in. That's required for warranty support! Same reasoning about seating rings. Interesting that aircraft companies are more honest about proper break-in than car companies, who say to take it easy. That's their lawyers speaking, not their engineers. I suppose there is more at stake (the aircraft engine alone is worth more than most cars) and the operators (pilots) are better trained than most drivers. Sure aircraft engines are different too: forged not cast, air cooled, static timed, magneto fired etc. In many ways they're like giant lawnmower engines. But they're horizontally opposed 4 and 6 cylinders like a Subaru, they run similar BMEP to car engines and rings need to seat properly just the same.
Note: New Lycoming & Continental piston aircraft engines require operation at 75% or greater power during the first 50 hours for break-in. That's required for warranty support! Same reasoning about seating rings. Interesting that aircraft companies are more honest about proper break-in than car companies, who say to take it easy. That's their lawyers speaking, not their engineers. I suppose there is more at stake (the aircraft engine alone is worth more than most cars) and the operators (pilots) are better trained than most drivers. Sure aircraft engines are different too: forged not cast, air cooled, static timed, magneto fired etc. In many ways they're like giant lawnmower engines. But they're horizontally opposed 4 and 6 cylinders like a Subaru, they run similar BMEP to car engines and rings need to seat properly just the same.
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I remember back in the day with 5.0 Mustangs, it was a pretty good bet that the ones that had been driven hard during break-in were the ones that were fastest in stock configuration. Oh, how our definitions of "factory fast" have changed! I don't know that the H-4 reacts similarly (mainly due to 30 years of machining improvements at the factory), and I know from experience that nobody is going to win a drag race with an FB25.
That said, I think driving normally on a new engine, whatever make or model, with some heavy throttle but avoiding full redline sweeps is a good way to break anything in.
That said, I think driving normally on a new engine, whatever make or model, with some heavy throttle but avoiding full redline sweeps is a good way to break anything in.
Patman
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When I bought my 98 Firebird Formula brand new, I broke it in really hard, and it did run quicker in the quarter mile than most others (12.68 at 111 with just a few small mods) but with my Corvette I broke it in really gentle, not going full throttle for the first 500 miles and not even going above about 3500 rpm. It runs very strong still, it's best 0-60 time according to it's onboard timer is 3.8 seconds. So I'm not so sure breaking it in hard is the way to go these days.
Asking someone the "best" break-in procedure is akin to asking for their astrological sign.
I followed Subaru's recommendation of doing the first OCI on my '18 Crosstrek at 6k. You can see the resulting UOA here. The engine (an FB20D, smaller but of similar construction to the FB25D that should be in a '19 Legacy) doesn't consume oil, and my fuel economy is great. Nb. the factory fill had an absolute boatload of antiwear additives in it. Also, the factory black oil filter is made by Tokyo Roki (as opposed to the blue filter made by Fram that you can buy from the dealership) and is generally considered to be pretty sturdy.
Originally Posted by KevinP
Asking someone the "best" break-in procedure is akin to asking for their astrological sign.
Yes sir. Or asking if the FF should be dumped early, then hold on for a wild ride. lol
Asking someone the "best" break-in procedure is akin to asking for their astrological sign.
Yes sir. Or asking if the FF should be dumped early, then hold on for a wild ride. lol
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