My family has been running amsoil in all of our vehicles for nearly 20 years. Its been good to us, it stays clean, our cars last, etc. Maybe three years ago i read on club lexus about someone using their ATF in their gs400 and how it stayed cleaner longer than Toyota fluid, ran cooler, and the such. So two years ago when i did a filter, drain, and refill on a rebuilt th350 on our van, it started slipping when cold in reverse a few weeks later then worse and worse till last year the transmission totally slips. Two years may sound like a while, but this is a fourth vehicle that gets started every 3 months (maybe) and goes around the block and parks again. So this total failure occured in probably less than half a tank of gas of switching to amsoil ATF which claims it its compatible with all types of ATF. When i did a drain and refill on my sc400 a year ago i also noticed some cold slipping in first a few months later and it still happens on my occasion. I am about to do another drain and refill, should i just go back to Toyota Type 4 or stick with the amsoil. Did it cause my van's tranny to fail? The van's fluid was also nice and red and clean before that last drain and fill. What about the lexus, different situation? Possibly erratic solenoid (its occurance is infrequent and unpredictable) or could this be related to the Amsoil
P.S. i noticed Mobil 1 and Catrol have atf's that claim to be compatible with
t IV

 

Its all about mileage my friend. This is my thoughts on transmission fluid changes. If its over 100K and you dont know if it has been changed, don't do it yourself. Take it to a dealer and make them responsible for it slipping. The oil gets into the clutch packs and when it gets thick it sticks there after being worn out, if you put new fluid in it releases all of that and starts to slip. I would just leave it alone if it has over 100K on it or take it to a dealer. I will NEVER change ATF over 100K period. Honestly I prolly won't change ATF at all due to the high risk.

 

i've been draining it and refilling it for the last 80k miles, that's how we do all of are cars, the fluid is very clean. Another drain and refill is coming up, so i'm trying to decide if i want to put in the amsoil again, or go back to toyota fluid like i always did before.

 

Just go back to Toyota Type T-IV or Mobile 3309, whichever one is cheaper. It's almost half the cost and works for its intended purpose.

I've always change my fluids regardless of mileage. I use to run Amsoil but it wasn't cost efficient over the long run. The Toyota/Mobil fluid with the combination of the cooler is already good as it is.

 

The Toyota Type IV is already synthetic yeah? I know the toyota stuff is good, but my sc400 tunnel always has had heat come through the transmission tunnel on long trips and i switched to amsoil that last time in hope of reducing temps, without a gauge it is hard to say.

 

if your tranny decides to fail after the fluid change then your tranny was on it's last leg anyway. atf doesn't kill trannies...lack of maintenace does.

 

Type IV is not synthetic.

The heat coming through the transmission is 'normal' on an SC. Both of my friend's SC300 does the same thing. We're going to add insulation to the floor to reduce the heat transfer into the cabin. It's annoying, but that's what happens when it lacks some insulation from the factory.