Im changing out the radiator an wanted to know the size of the o rings on the transcooler lines .

 

Shouldn't be any O-rings. They should be flared, similar to a brake line (but much larger)

 

If i recall correctly last radiator had them...
There on the end on left side

 

I would just remove one of the old rings are take it to the hardware store and match it up. The last couple rads I changed I didn't even think of changing those rings and they've been fine though

 

I wanted to have em there while it is off..
I bought a assortment so i can match them .
But i also wanted to know can any o ring from auto store handle the transmission fluid ?
I also have the plumbing ones but not sure they handle it.
Thanks

 

I guess you would have to find information about what it's made out of, or see if the package says what's safe and what's not.

 

any O-ring will generally work. ATF isn't that terrifyingly acidic or basic.

 

Go to a transmission shop or dealer to get them. The heat will cause regular o-rings to fail.