Subaru Forester Oil Consumption (FB25): Causes & Fixes

If your Subaru Forester keeps asking for a top-up between oil changes, you're not imagining it. The FB25 engine has a known oil consumption issue, and it's affected a big chunk of Foresters on the road today. Here's what's actually going on, which years are affected, and what your real options are.

Which Foresters Are Affected (Years & FB25)

Yes, several Forester model years with the FB25 engine are known for above-average oil consumption, mainly cars built in the early to mid 2010s.

The FB25 is Subaru's 2.5L boxer engine that replaced the older EJ25 starting around 2011. It showed up in the Forester, Outback, and Legacy. The years most commonly linked to oil consumption complaints are roughly 2011 through 2016, though it can show up outside that window too.

If you're shopping used, don't panic and rule out every FB25 Forester. Plenty of these engines run fine with proper maintenance. But it's worth knowing the history before you buy, and worth watching your oil level closely if you already own one.

Why the FB25 Burns Oil (Ring Design)

The FB25 burns oil mainly because of a piston ring design issue that lets oil seep past the rings and into the combustion chamber, where it gets burned off.

Piston rings are supposed to seal tightly against the cylinder wall. This controls oil, keeps compression where it belongs, and stops oil from sneaking into the combustion chamber. On the early FB25, the ring design didn't seal as well as it should have. Over time and heat cycles, this let small amounts of oil slip past and burn along with the fuel.

The result isn't usually a leak you'll see on your driveway. Instead, the oil just quietly disappears from the dipstick. Many owners don't notice until the low oil light comes on, which is honestly too late for comfort.

Subaru later revised the ring design in newer production, which is why not every FB25 has this problem to the same degree. Build date and production changes matter more than the model year printed on the title.

How Much Oil Loss Is "Normal"?

Some oil consumption is normal in most engines. The line gets blurry when it becomes excessive.

How much oil consumption is normal for a Forester? Losing less than a quart between scheduled oil changes is typically fine, but needing a quart every 1,000 miles or so points to a real problem.

The safest habit is checking your dipstick every 1,000 miles, especially if you own a Forester from the affected years. It only takes a minute and it can save you from a much bigger repair bill down the line.

Subaru's Response (TSB / Class Action)

Is FB25 oil consumption covered by a TSB or warranty? Subaru issued technical service bulletins addressing oil consumption on affected engines, and the issue was also the subject of a class action lawsuit.

Subaru released TSBs instructing dealers on how to test for excessive consumption and, in some cases, how to address it, which sometimes included piston ring replacement or other internal repairs. Beyond the TSBs, Subaru faced a class action lawsuit tied to oil consumption complaints across several models using the FB and FA engine families.

We're not going to guess at settlement numbers or coverage details here, since those specifics have changed over time and vary by case. If you think your Forester might qualify for anything under a past claim or extended warranty, your best move is checking directly with a Subaru dealer or the official Subaru of America consumer resources, and searching NHTSA's database for related bulletins on your specific VIN.

If you do go the dealer route, it helps to walk in prepared. Dealers typically run a documented oil consumption test, which means driving a set number of miles and measuring exactly how much oil is used. Keeping your own log of fill ups, mileage, and oil added before your appointment can make that process faster and gives you a paper trail if you need to escalate the claim.

Fixes: Monitoring, Repair, or Engine Replacement

Can Forester oil consumption be fixed? In some cases yes, through a dealer-approved repair like piston ring replacement, but severe or long-ignored cases often call for a full engine replacement.

Your options generally break down like this:

• Monitor and top up. If consumption is mild and you're diligent about checking oil, some owners simply live with it and stay ahead of the level.
• Dealer repair under TSB. If your car qualifies and the consumption is documented as excessive, a dealer repair may address the ring issue directly.
• Aftermarket ring job. An independent shop can perform a ring replacement, though this is labor intensive since it usually means pulling the engine apart.
• Engine replacement. If consumption has already caused wear, low compression, or you just want to stop worrying about it, swapping in a different engine is often the more practical long-term fix.

When should I replace the FB25 engine? Once oil consumption is severe, has caused a check engine light for misfires or low oil pressure, or repair costs start approaching replacement cost, a replacement engine is usually the smarter call.

Choosing a Low-Mileage Replacement Engine

If you're leaning toward replacement, a low-mileage JDM FB25 is worth serious consideration over a full rebuild. JDM engines typically come from vehicles pulled from Japan's stricter inspection and mileage system, which often means less wear for the miles shown.

A few things to check before you buy any replacement engine:

• Confirm it's the correct FB25 variant for your exact Forester trim and year.
• Ask for compression numbers or a run video if the seller offers one.
• Check that the timing chain and covers are included, since these add up fast if missing.
• Look for a warranty period on the engine itself, not just the shipping.

We carry a tested Subaru Forester FB25 engine (DOHC 2.5L, JDM, timing chain included) covering the 2011 through 2016 range, which lines up with the model years most affected by this issue. You can browse our full JDM Engines collection if you're comparing options or need a different displacement.

Frequently Asked Questions

Why does my Subaru Forester burn oil?
The early FB25 has a piston ring design that lets small amounts of oil slip past into the combustion chamber and burn off.

Which Forester years have oil-consumption problems?
Mainly Foresters from roughly 2011 through 2016 with the FB25 engine, though it can appear outside that range too.

Is FB25 oil consumption covered by a TSB or warranty?
Subaru issued TSBs on the issue, and it was also part of a class action lawsuit. Check with a dealer or Subaru of America for current coverage.

How much oil consumption is normal for a Forester?
Under a quart between oil changes is generally fine. A quart every 1,000 miles or less is excessive.

Can Forester oil consumption be fixed?
Yes, through monitoring, a TSB repair, a ring job, or in more severe cases, a full engine replacement.

When should I replace the FB25 engine?
When consumption is severe, causing performance issues, or repair costs get close to the cost of a replacement engine.

Related Reading

Before buying any used engine, walk through our guide on How to Inspect a Used Engine Before You Buy so you know exactly what to check.