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Lexus GS300 Gear Indicator Stuck at 4 and Slipping: How We Overhauled the Gearbox and Replaced the Torque Converter

This Lexus GS300's gearbox was slipping, and its gear indicator was stuck showing gear 4. Here is what we found inside and what we did.

Job completed: June 2026

White Lexus GS300 at our Singapore workshop for a gearbox overhaul and torque converter replacement

Job completed: June 2026. Last updated: October 2026. Written from our workshop job records and photos; technical details are generalised where the records do not confirm them.

Car2010 Lexus GS300 (3.0L V6 petrol)
SymptomGear indicator stuck showing gear 4, and the gearbox slipping on our test drive
Fault foundWorn clutches, hardened rubber seals that let the pressure drop, and a slipping torque converter
Repair doneFull gearbox overhaul with the internal consumables and a reconditioned torque converter, refilled with the correct ATF
PartsOverhaul consumables and a reconditioned torque converter
Time takenTimeline given with the quote
CostQuoted before work: gearbox overhaul $2,380, reconditioned torque converter $950
Warranty2 years / 40,000km on the gearbox overhaul

What the owner reported

The owner first asked us to quote a gearbox overhaul for this 2010 Lexus GS300, with the parts included and the downtime, and wanted a test drive check before committing. On that test drive our team found the gearbox slipping. The owner also told us the gear indicator was stuck showing gear 4.

A gearbox that slips is not something to keep driving on for long. The longer it runs like that, the more the inside wears. The owner wanted a clear answer and a firm price before any work started, not a guess.

White Lexus GS300 in for a gearbox overhaul at our Sin Ming workshop in Singapore

The car

The car is a 2010 Lexus GS300 with the 3.0L V6 petrol engine and a conventional automatic gearbox. The torque converter sits between the engine and the gearbox and passes the power across using fluid. Inside the gearbox, clutch packs grip and release to change gears.

Over many years and a lot of kilometres, those clutch packs wear and the torque converter can fail. When that happens the gearbox slips, holds a gear, or shifts roughly. Opening the gearbox up shows exactly which parts are worn.

How we diagnosed it

We test drove the car before anything was decided, and the gearbox slipped. The overhaul and a reconditioned torque converter were quoted then, before any work began.

Once we opened the gearbox, the picture was clear. The clutches were worn and had been slipping. The rubber seals inside had hardened, so the gearbox could not hold its pressure. The torque converter had been slipping along with the gearbox. Together those explained the slipping we felt on the test drive.

We sent the owner videos and photos of what we found.

Torque converter on the workshop floor during the Lexus GS300 gearbox overhaul in Singapore

Why an automatic gearbox slips

Inside an automatic gearbox, clutch packs do the hard work of changing gears. They wear a little every time they grip and release. On a car of this age that wear adds up, and the clutch packs start to slip. Rubber seals harden with age too, and once they stop sealing, the gearbox loses the pressure it needs to hold its clutches.

The torque converter ages too. When it slips it can no longer pass the engine's power cleanly into the gearbox, which makes the slipping worse. This is normal ageing, not something the owner did wrong. A fluid change alone does not bring back worn clutch packs or a slipping converter, so the proper fix is to overhaul the gearbox and replace the converter.

What we did

We did the job properly rather than patch it and hope.

  • Removed the gearbox and stripped it down completely.
  • Overhauled it with the consumable parts inside the gearbox casing, including new clutches, rubber seals, gaskets and the filter.
  • Replaced the slipping torque converter with a reconditioned unit.
  • Refilled with the correct ATF.

We sent the owner videos and photos once the gearbox was open. The overhaul carries a 2 year / 40,000km warranty.

Lexus GS300 automatic gearbox stripped down for an overhaul, internal clutch packs and parts laid out

Before and after

Before

  • Gear indicator stuck showing gear 4
  • Gearbox slipping on our test drive
  • Worn clutches, hardened rubber seals and a slipping torque converter inside

After

  • Gearbox overhauled with new clutches, seals, gaskets and filter
  • Reconditioned torque converter fitted
  • Refilled with the correct ATF

What a Lexus gearbox overhaul and torque converter repair costs in Singapore

On this GS300 the gearbox overhaul was quoted at $2,380 when the owner first asked, and the price held after our test drive. That covers the consumable parts inside the gearbox casing, such as the clutches, seals, gaskets, filter and transmission oil, plus the bearings and pistons, and the overhaul carries a 2 year / 40,000km warranty. The reconditioned torque converter was quoted at $950 on top.

What moves the price is what the gearbox needs beyond the overhaul. Replacing the torque converter or the valve body is not part of the overhaul price, so those are quoted separately when they are needed. This is why we test the car and quote before any work begins.

How to catch it early

The earliest signs are small. A gearbox that jerks on a shift, hesitates before it engages, or slips so the engine revs climb without the car pulling. If the gear shown on the dash does not match how the car is driving, that is a warning too.

Catching it early matters. A slipping gearbox wears itself faster the longer it runs, so a small problem can grow into a full overhaul. Changing the ATF on schedule and getting any slip or jerk checked early gives the gearbox its best chance, and lets us fix a small fault before it damages the rest of the box.

About the workshop

This Lexus GS300 (Gearbox overhaul) was handled at 1 Car Service, an independent workshop in Sin Ming AutoCity, Singapore. The work is backed by our 2-year, 40,000km warranty. We hold a 4.9★ rating from 1,836+ Google reviews.

When to get your gearbox checked

Gearbox slipping or stuck in gear? Get it checked.

WhatsApp us your car model, year and what the gearbox is doing. We'll tell you what is likely wrong and what it costs before any work begins. A full gearbox overhaul is backed by a 2 year / 40,000km warranty.

WhatsApp us - free gearbox check

Lexus GS300 gearbox overhaul: common questions

How much does a Lexus gearbox overhaul cost in Singapore?

It depends on the car and what the gearbox needs. On this GS300 the overhaul was quoted at $2,380, covering the consumable parts inside the gearbox, with a 2 year / 40,000km warranty. The reconditioned torque converter was quoted at $950 on top. We test the car first, then quote before any work begins.

Why is my Lexus GS300 gearbox slipping?

On this GS300 the clutches inside the gearbox were worn, the rubber seals had hardened so the gearbox could not hold its pressure, and the torque converter was slipping too. A slipping gearbox needs a proper check: a test drive first, then a look inside once it is opened.

Can a fluid change fix a slipping gearbox?

Only if the fluid is simply old or low and nothing inside is worn. Once the clutch packs are worn or the torque converter has failed, fresh fluid does not bring them back. The proper fix is to overhaul the gearbox and replace the failed parts, not just change the oil.

How long does a gearbox overhaul take?

A full overhaul like this GS300's is not a while-you-wait job. The gearbox has to come out, be stripped down, overhauled with new internal parts, then refitted and tested. We give you the timeline with the quote.

Is the gearbox overhaul covered by a warranty?

Yes. A full gearbox overhaul at our workshop carries a 2 year / 40,000km warranty, whichever comes first. We confirm the exact terms with you before the work starts.

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