Mk3 Gs430 Transmission Oil Change + Shift Issues

mixls400 · July 31, 2015

Hi all, I've owned my 2005 gs430 a few months now and am really pleased with it. My only concern is that when changing up, the final shift into top gear seams to take 2 attempts to engage. And when I lift off in top gear and then reapply the throttle, the engine revs increase before settling again. Is this normal or just mine that's doing it ?

I decided to change the oil after doing some internet research to see if this would help. Its actually relatively easy but the oil had some fine metal deposits in it. This may be acceptable as the car has done 95000 miles. The problem is you only get a fraction of the fluid out so I've done 3 changes up to now.

I actually modified my box by incorporating a fill tube into a new fill plug I bought, that runs up into the engine bay and is capped off. This makes changing the oil a lot easier. My next plan is to purchase a new filter / strainer and fit this before adding new fluid and flushing the old fluid out through the front cooler. It takes longer but ensures the old oil is pushed out and replenished with new clean oil. I'm hoping this helps with the shifting issue mentioned earlier before going down the solenoid route.

I know these transmissions are 'sealed for life' but any oil no matter how good is going to loose performance over time due to wear and tear. 95000 miles is a lot to ask of an oil and the filter must be at choking point,

I'll keep you updated as to my progress and will gladly pass on any help / advise on if anyone else wants to change their oil.

Mike.

ColinBarber · July 31, 2015

The transmission typically won't go into top gear before it is up to temperature.

What speed are you travelling when you experience the revs issue? Before a certain speed the transmission won't be in lock-up so there would be a rev rise as the extra power goes to the torque convertor.

steve2006 · July 31, 2015

It's concerning to hear of the fine metallic particles being present in the fluid, the sump is normally fitted with several magnets to pull these out of the fluid in the sump.

The drain refill process is a pain with around only 2 litres being drained on each occasion, it can be flushed via the oil cooler but there are reports both good and bad regarding this method as previously trapped contaminants can be released into the flow of fluid.

As Colin mentioned the Aisin transmissions are fitted with a fluid temperature sensor which prevents upshifts to top gear until the transmission reaches a certain temperature in order to protect it.

The main thing is to ensure the specified Toyota fluid only is used that being Type IV.

If you do replace the filter block be aware that the sump requires a special sealant for refitting and sump bolt torque settings are crital to prevent future leaks.

ColinBarber · July 31, 2015

Definitely agree on using Toyota fluid, or the OEM alternative, although for that age of vehicle I'd guess you need Toyota WS rather than T-IV - your manual should confirm that.

mixls400 · August 1, 2015

Hi again, I could be travelling at 70 mph and lift off momentarily and when I accelerate again gently it revs before settling down. If I accelerate hard its not noticeable. Am I being too gentle with it or is it linked to the metallic particles I mentioned earlier ?

I contemplated getting another transmission for it as I found one for sale. It had supposedly done 10000 miles, was out of a 2009 model and is in Lithuania via a breakers in America ?? He said to check the label on top of mine to see whether its compatible. He's asking £550 for it but I have my doubts as I cant prove the mileage or whether it exists at all. There seems to be a lot breaking in America but not many over here.

ColinBarber · August 1, 2015

how many revs does it rise?

Not many GSs sold in the UK and most where hybrids, hence the lack of second hand parts available.

mixls400 · August 17, 2015

Hi sorry for the delay, been away on hols, when I lift off in top gear there is a little blip on the rev counter needle and then when I re apply the throttle the revs are around 3 - 400 higher before settling down again. It doesn't seem to be as bad now as when I first bought it but I have changed the auto transmission oil a few times now and intend to purchase a new strainer to go inside the sump and do a more thorough oil change including oil cooler, pipes and fluid coupling as all I seem to be doing is mixing old and new oil at the moment.