GS430 with 178k miles. Is a tranny flush or drain and fill more appropriate?

 

i'd say drain and fill for sure. I just did around 5 drain and fills over time on my 98 ls400 and dropped the pan one of those times to change the filter. flushes do a good job of getting sludge out of the tranny, but there is more risk involved when you have a high mileage car.

only use toyota type IV fluid!

 

Thanks man!

 

I drained and refilled once and that was a bad idea. The new fluid thinned out and I got bad shifts from a cold start. It took a few drain and refills to get it back to normal.

 

You can do the drain and fill method or do it the way I do.

Drain and Fill
Remove return line from radiator to transmission.
Run engine until 2 qts come out.
Refill with 2 Qts.
Repeat until fluid coming out is clean.

May take over 12 qts to do this.

 

so....bad idea to switch out old fluid with new fluid, eh? as long as you mix the same type of tranny fluid, you should be fine.

 

never tried this before but sounds good. I was under the impression the full capacity of the transmission was ~9quarts?

 

I've always done 2 drain and fills a week apart each year. I get about 3.5 quarts out each time and I feel it's been more than adequate, and I've experienced smoother shifts

 

One drain and refill was the mistake. It takes multiple. At least in my case

 

This is definitely an exception, not the norm. There must of been something else at play in you case. A proper drain and fill alone will not cause the issues you were encountering.

 

Has anyone used anything other the Genuine Toyota T IV fluid? Surely modern ATFs would supersede this standard by now.

 

I've always used T-IV because at my Toyota dealer ts actually cheaper than anything else, but I've seen other people use a Valvoline synthetic with good results

 

What about a 2005 GS430 with 76k on it, Drain and fill, flush or drop the pan? I've been reading lots of post on this topic lately as my mechanic I use says the trans. fluid is getting dirty and he usually drops the pan for this....Should I just tell him to drain and fill? Former mechanic I had for my GS400 dropped the pan and I could never stop the leak from the pan.... thats my only concern.

 

Unless your GS is modded, or has Supra tranny, use T-IV. You can never go wrong with OEM.
A drain and fill is the safe way to maintain your trans.
Removing the cooler return line from the radiator is more involved.

The service schedule recommends a trans flush every 60,000 miles.

 

Check fluid level COLD, mine did this for ages till I realized that when COLD the fluid was below the cold line and it WAS the issue. 261k miles now, solid as a rock.

It was good warm, but NOT good cold, and the colder it got the worse

Check it cold, colder the better.