The O-rings sit on top of the filter housing cap, not on the filter itself

The 2015 Chevy Trax has two rubber O-rings that seal the oil filter housing cap to the engine block. These rings are located on the underside of the cap — the part you unscrew to access the filter cartridge inside. When you remove the cap, you'll see the O-rings sitting in grooves on the cap itself, not attached to the filter element. One ring sits in a shallow groove closer to the outer edge, and the second sits in a deeper groove closer to the center where the cap threads down.

The housing cap is mounted on top of the engine, toward the front and slightly to the driver's side. On the 2015 Trax, it's a black plastic cap roughly three inches in diameter. You don't need to remove anything else to reach it — it's one of the first things you'll see when you open the hood and look at the top of the engine.

Key Takeaways

  • The two O-rings are located on the underside of the oil filter housing cap, sitting in grooves on the cap itself.
  • The housing cap is a black plastic piece on top of the engine that you unscrew by hand or with a filter wrench.
  • Both O-rings should be replaced every time you change the oil, even if they look fine.
  • New O-rings come with most replacement filter kits for the 2015 Trax, or you can order them separately from a parts supplier.

Why both O-rings matter, even though only one gets wet

The outer O-ring creates the seal between the cap and the housing. The inner O-ring seals around the filter cartridge itself as it sits inside the cap. Both rings wear out at the same rate because they're both under pressure every time the engine runs. If you replace only one, the other will eventually harden and crack, and you'll have an oil leak that pulls you back into the same job within a few months.

Most people don't think about the inner ring because they can't see it while the cap is on. But it's doing the same work as the outer one, and it fails just as often. Replacing both at once costs almost nothing extra and saves you from a repeat visit to the engine bay.

What to buy and where the parts come from

The part number for the O-ring kit on a 2015 Chevy Trax is GM 12640957. This kit includes both O-rings and usually costs between $8 and $15 from a parts store. You can also order the rings individually — the outer ring is GM 12640957A and the inner ring is GM 12640957B — though buying them as a kit is usually cheaper.

Most oil filter kits sold for the 2015 Trax include new O-rings in the box, so check what came with your filter before you order separately. If you're buying a filter cartridge alone, the rings are not included and you'll need to order them. Chevy dealerships stock them, as do AutoZone, O'Reilly Auto Parts, NAPA, and Advance Auto Parts. Online retailers like RockAuto and Amazon also carry them, though shipping may take longer than a local pickup.

How to remove and install the new O-rings

Start by unscrewing the housing cap. You can do this by hand if the cap isn't too tight, but a filter wrench makes it easier — use the wrench that fits a cap about three inches across. Once the cap is off, you'll see the old O-rings in their grooves. Pry them out gently with a plastic spoon or a soft plastic tool; don't use a metal screwdriver because you can scratch the grooves and ruin the seal.

Before you install the new rings, wipe the grooves clean with a lint-free cloth. Any dirt or old rubber left behind will prevent a tight seal. Lightly coat the new O-rings with fresh oil — use the same oil that goes in your engine — and press them into their grooves by hand. The outer ring goes in the shallow groove first, then the inner ring in the deeper groove. They should sit flat and even all the way around with no twists or folds.

Once both rings are seated, screw the cap back on by hand until it's snug, then tighten it another quarter turn with the filter wrench. Don't over-tighten; the rings do the sealing, not brute force. If you crank too hard, you'll damage the plastic cap or crush the rings.

Signs that your O-rings need replacing right now

An oil leak from the top of the engine, near the filter cap, is the clearest sign. The leak will be a slow drip or a small puddle under the cap, not a gush. You might also notice the oil level dropping faster than usual between changes, or you might smell hot oil burning on the engine block when you drive.

If you've never replaced the O-rings and your Trax has more than 50,000 miles on it, they're due for replacement whether or not you see a leak. Rubber hardens over time, especially in an engine bay where temperatures swing wildly. By the time a leak shows up, the rings have usually been failing for weeks.

What happens if you ignore a leaking cap

A slow leak from the housing cap won't destroy your engine when ready, but it will cost you oil. You'll need to top off the oil more often, and if you miss a top-off, the engine can run low and suffer damage. Oil also drips onto hot engine parts and burns, creating smoke and smell. Over time, the leak gets worse as the rings harden further, and you might eventually lose enough oil to trigger a low-oil warning light.

The repair itself takes 15 to 20 minutes once you have the new O-rings, so catching it early and replacing them during your next oil change is much simpler than dealing with a major leak or an engine that's run low on oil.

Frequently Asked Questions

Can I reuse the old O-rings if they still look okay?

No. O-rings harden invisibly over time, and a ring that looks fine can fail within weeks. The cost of new rings is so small compared to the risk of an oil leak that it's never worth reusing them. Replace both rings every time you change the oil.

What if I install the O-rings backwards or in the wrong grooves?

The rings are identical, so there's no backwards or forwards. But putting them in the wrong grooves will cause a leak. The outer ring goes in the shallow groove, the inner ring in the deep groove. If you're unsure which is which, the deep groove is the one closer to the center of the cap.

Do I need a special tool to remove the housing cap?

A filter wrench makes it easier, but you can unscrew the cap by hand if it's not too tight. If the cap is stuck, a filter wrench prevents you from stripping the plastic. A wrench sized for a three-inch cap works on the 2015 Trax.

How often should I replace these O-rings?

Replace them every time you change your oil. They're inexpensive and included in most filter kits, so there's no reason to skip them. If you change your oil every 5,000 to 7,500 miles, you'll replace the rings on that same schedule.

What if oil is leaking but I can't see it coming from the cap?

Oil can run down the side of the engine and drip from a different spot than where it's leaking. Check the cap area with a clean rag while the engine is cold, then run the engine and check again. If the cap area is wet and the rest of the engine is dry, the leak is coming from the O-rings.