Mele Engine Bay Cap Set for 15+ STI: Install Guide
By Custom Shift Knobs & Interior Mods | Published: 2026-10-27
Category: How-to Guides
Learn how to install the Mele Engine Bay Cap Set on your 2015+ Subaru STI. Step-by-step instructions, common mistakes, and tips for a clean engine bay upgrade.
Quick answer
Replacing your factory engine bay caps with a Mele Engine Bay Cap Set takes about 20 minutes and requires only basic hand tools. Follow the steps below to avoid cross-threading and ensure a secure fit.
Why upgrade to a Mele cap set?
The Mele Engine Bay Cap Set replaces the stock plastic caps on your 15+ STI with machined aluminum pieces that resist fading and cracking. The set includes caps for the oil filler, washer fluid, power steering, and coolant reservoirs, and it comes in a range of anodized and powdercoated finishes so you can match or contrast your engine bay color.
One trade-off: the powdercoated finishes are more durable against chips than anodized options, but they may not match an anodized finish from another brand exactly. If color consistency matters, stick with all Mele caps.
Installation steps
- 1. Remove the old caps: Twist each factory cap counterclockwise until it releases. Set them aside in a clean area. Do not use pliers or force; some caps may be tight from heat cycling. If a cap is stuck, let the engine cool completely before trying again.
- 2. Clean the threads and mating surfaces: Wipe each reservoir opening with a lint-free cloth to remove dirt, oil, or old sealant. This prevents debris from interfering with the seal. Avoid using solvents that could leave residue inside the reservoir.
- 3. Install the new Mele caps: Screw each Mele cap on by hand until it seats snugly. Do not overtighten—aluminum threads can strip more easily than plastic. A firm hand-tight is sufficient. If the cap does not thread smoothly, you may have the wrong cap for that reservoir; stop and verify the fit.
- 4. Verify the seal and check for leaks: Start the engine and let it idle for 2 minutes. Inspect each cap for coolant or fluid seepage. Wipe away any excess and re-tighten gently if needed. A small amount of coolant weep can indicate an incomplete seal—re-seat the cap rather than forcing it.
Product details
- Mele Engine Bay Cap Set - 15+ STI: Available in 9 finishes: Black, Red, Blue, Silver, Gloss White, Hyper Teal, Hyper Pink, Neon Yellow, and Red Wrinkle. Custom color option available. You can match your car's exterior or choose a contrasting accent without buying a custom set.
Mele Engine Bay Cap Set - 15+ STI
