122k miles on my 2018 Highlander… What maintenance should I do?

Technical Issues Discussions
1

My Highlander has 122,000 miles, and I’ve been doing oil changes with synthetic oil from Walmart every 5,000 miles. I haven’t seen any warning lights, and the car feels fine. The last full inspection was back at 90,000 miles. Should I get it inspected now even though nothing seems off?

2

At 122,000 miles, you’ll want to check the following if they haven’t been done:

  • Spark plugs: Should’ve been replaced at 100K miles.
  • Transmission and differential fluid: These need changing every 50-60K. If they’ve never been done, it might be too late to prevent wear, but it’s worth a try.
  • Drive belt: Replace it as preventative maintenance.
  • Filters: Replace engine air, cabin air, and fuel filters.
  • Tires: Check tread depth on all tires, including the spare.
  • AC system: Service it to keep it running smoothly.
  • Fuel system: Add a bottle of fuel injector cleaner to a full gas tank to help clear out deposits.
3

@Claire
Doesn’t the 2018 Highlander have a timing chain instead of a belt?

4

RuthMitchell said:
@Claire
Doesn’t the 2018 Highlander have a timing chain instead of a belt?

Yep, it’s a chain, not a belt.

5

RuthMitchell said:
@Claire
Doesn’t the 2018 Highlander have a timing chain instead of a belt?

Exactly, and spark plugs are recommended every 60K, not 100K.

6

@Claire
Thanks for the advice! I bought the car with 90K miles, and aside from oil changes and inspections, I haven’t done much. I might try some of this myself or find a mechanic if it’s too complicated.

7

@Rav4Rider
Thanks for being so polite! It’s refreshing to see someone appreciative on here.

8

@Claire
Can you explain why it might be too late to change transmission or differential fluid? My 2018 XLE is at 92K, and I’ve been consistent with oil changes but neglected those two.

9

Mack said:
@Claire
Can you explain why it might be too late to change transmission or differential fluid? My 2018 XLE is at 92K, and I’ve been consistent with oil changes but neglected those two.

When the transmission wears over time, tiny metal particles from the gears end up in the fluid. If the fluid hasn’t been changed regularly, those particles actually help fill the gaps caused by wear. Replacing the fluid suddenly can remove those particles and cause slipping or delayed shifts. It’s a tricky balance with higher mileage vehicles.

10

@Claire
I think they meant the serpentine or drive belt, not a timing belt. Transmission fluid can be changed at 100K, but make sure it’s just a drain and fill, not a full flush. For spark plugs, get high-quality ones rated for 100K miles to avoid needing frequent replacements.

11

@Ethan
I saw a video on YouTube where they removed the intake manifold to reach the rear spark plugs. It looks tricky but doable. I might give it a shot when it’s warmer—it’s currently freezing where I live!

12

@Rav4Rider
Good luck! It’s pretty cold here too. Stay warm and let us know how it goes.

13

Here’s a quick checklist for maintenance:

  • Spark plugs at 60K miles
  • Coolant change at 100K miles
  • Brake booster vacuum pump at 120K miles

My 2018 Limited is approaching 100K, so I’ll be tackling these soon too.

14

If you’ve only been doing oil changes, your air filter and cabin air filter probably need replacing—they’re easy to do yourself.

I’d also recommend:

  • Transmission and differential fluid changes (especially if you have AWD)
  • A general inspection by a trusted mechanic if you’re not comfortable doing it yourself. They’ll check for leaks, worn rubber components, and other potential issues.

Here’s a link to Toyota’s official maintenance guide for your car: Maintenance Manual PDF. Check page 53 for 120K-mile recommendations.