Hi, I have 98 Maxima with automatic transmission, today I noticed the radiator is leaking, so I have to replace it. I've done it once before about 10 years ago. But I don't remember how I went about the ATF hoses that connect to the bottom of the radiator. I don't know much about cars, just trying to do easy jobs with online tutorials.
1. I read that about a quart of ATF fluid will leak out, but would it be possible to minimize it by lifting radiator up partially and then disconnecting the hoses?
2. Should I clamp the ATF rubber hoses, or would that damage them since they are 25 years old? Maybe I should just tape them somewhere pointing up so they don't leak out?
3. Questions about the ATF fluid if it leaks out. I had mechanic change it a couple years ago, and I'm not sure which type of fluid he put in, an official Nissan one or something else, would it be OK to use Dexron III/Mercon automatic transmission fluid even though mechanic filled Nissan fluid, or vice versa? Also, can I use Dexron IV or later instead, are they backwards compatible like motor oils? Which ATF fluid should I buy?

 

I believe you can use dexron fluid, and since you're changing the radiator, I would recommend you replace the hoses as well, especially since you said they're over ten years old.

 

There are special hose clamps you can buy to squeeze the lines shut that won't harm rubber, but all bets are off if your hoses are already deteriorated. If you replace the hoses (which I recommend you do) make sure you get hoses that are rated for ATF; HP fuel lines and vacuum hoses are not compatible. I always prefer OEM ATF, but it may not be super critical for an older trans like this. I'm pretty sure Dex IV is backwards compatible with III, but read the label to confirm.

 

Didn't end up having to clamp the transmission hoses, just pulled the radiator up a bit and pulled hoses off and made sure to tape them facing up, so nothing leaked out, only about half a cup of fluid leaked from radiator. I spoke to mechanic and he said to just put Dexron III, so I'll do that in the near future. After radiator replacement, the transmission fluid level dropped from 100% normal range (maximum) to 20% normal range.