The “AT OIL TEMP” warning refers to your automatic transmission oil temperature , not your engine oil.

What “AT OIL TEMP” Means

  • “AT” = automatic transmission.
  • “Oil temp” = temperature of the transmission fluid inside the gearbox.
  • When the light comes on (especially if it’s flashing), it means the transmission fluid is overheating and can no longer safely protect the transmission components.

On many cars (especially Subarus), this light is specifically a warning that the automatic transmission fluid (ATF) is too hot and that you risk damaging the transmission if you keep driving hard or for long in that state.

Think of it like a “fever” indicator for your gearbox rather than your engine.

Common Reasons It Comes On

Typical triggers include:

  • Long uphill climbs or mountain driving.
  • Heavy stop‑and‑go traffic on a hot day.
  • Towing or carrying a heavy load.
  • Slipping transmission, low or old ATF, or a failing transmission cooler.
  • Internal transmission fault or sensor issue (sometimes the light indicates a general AT problem).

In many cars, normal transmission fluid operating temps are around the low 200 °F range; once it gets significantly hotter than that, wear and damage speed up.

What You Should Do If It Lights Up

If the AT OIL TEMP light turns on or starts flashing while you’re driving:

  1. Safely pull over as soon as you can.
  1. Put the car in Park, keep the engine idling for a bit or shut it off, and let everything cool down.
  1. Avoid hard acceleration, high speeds, towing, or steep hills when you start driving again.
  1. If the light keeps coming back, have a mechanic check:
    • Fluid level and condition
    • Transmission cooler and lines
    • Any stored transmission fault codes

Continuing to drive with the light flashing can overheat and break down the fluid, damage seals and clutches, and eventually kill the transmission.

Quick FAQ Style Scoop

  • Q: Is it safe to drive with the AT OIL TEMP light on?
    A: Only long enough to get to a safe place to pull over; you should not continue normal driving with it on, especially if it’s flashing.
  • Q: Does it mean my engine oil is low?
    A: No. It’s about automatic transmission fluid temperature, not engine oil level.
  • Q: Do I need a shop right away?
    A: If it happened once in extreme conditions and went away after cooling, you’re probably okay but should mention it at your next service. If it happens repeatedly or quickly, get it checked soon.

Bottom line: “AT OIL TEMP” means your automatic transmission fluid is too hot , and you should slow down, cool the car, and get the transmission inspected if it keeps happening.

Information gathered from public forums or data available on the internet and portrayed here.