---
id: guide-0014
title: "Which fluids and filters matter, and when do I change them?"
category: guide
subtopic: maintenance-fluids
page_type: guide
source_url: "https://www.castlecdjrnaperville.com"
tags: ["maintenance", "fluids", "filters", "service", "mileage"]
questions:
  - "What fluids does my car need?"
  - "How often do I change oil?"
  - "When do I change air filters?"
  - "What about coolant and transmission fluid?"
related: [maintenance-schedule, ordering-parts]
dealer: Castle CDJR of Naperville
---

## Fluids That Keep Your Vehicle Running

Regular fluid and filter changes are the backbone of vehicle health. Here's what matters:

### Key Fluids & Service Intervals

**Engine oil & filter:** Every 3,000-10,000 miles (check your manual; modern oils last longer).

**Air filter:** Every 12,000-15,000 miles or when visibly dirty.

**Cabin air filter:** Every 12,000-15,000 miles for cleaner air inside.

**Coolant:** Every 30,000-100,000 miles (varies by vehicle type).

**Transmission fluid:** Every 30,000-100,000 miles; some vehicles use "lifetime" fluid-check your owner's manual.

**Brake fluid:** Every 2 years, regardless of mileage; it absorbs moisture over time.

**Power steering fluid:** Every 50,000-100,000 miles.

## Stay on Track

Your owner's manual has your exact schedule. Castle CDJR of Naperville's Service team knows every Jeep, RAM, Dodge, and Chrysler inside out. Call **(630) 864-6683** to book a fluid check or get a personalized service plan.