Mixing ATF?
Thread Starter
Burning Brakes
Joined: Sep 2017
Posts: 1,069
Likes: 63
From: Belgium
Mixing ATF?
Hi everyone
Can mineral, semi-synthetic or synthetic AT fluid be mixed in a TH350 (1977)?
I don't know what the PO used...
I asked a shopkeeper from a local automotive store but he said he isn't sure. He only had synthetic AT fluid in stock.
So before I buy anything I want to be sure of this.
Also:
What if the fluid of the tranny has a dark brown color? Should I be worried?
Can mineral, semi-synthetic or synthetic AT fluid be mixed in a TH350 (1977)?
I don't know what the PO used...
I asked a shopkeeper from a local automotive store but he said he isn't sure. He only had synthetic AT fluid in stock.
So before I buy anything I want to be sure of this.
Also:
What if the fluid of the tranny has a dark brown color? Should I be worried?
Instructor
Joined: Aug 2012
Posts: 109
Likes: 21
From: Dripping Springs Texas
The dark trans fluid is not good. If it were me I'd take it to a shop that can truly flush the whole trans and get all the old fluid out and then drop the pan and replace the trans filter. If after driving the car a while, the dark trans fluid reappears, you have likely have trans bands that are going or are bad and a rebuild is the only remedy. I say this because I've had this happen to me. Good luck, hope a fluid flush and filter change is all you need.
Last edited by Saddlehorn; Sep 21, 2020 at 07:24 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Can you mix those fluids? I think so; but I wouldn't keep what you have anyway. Just have the fluid purged (as best an oil change place can do) and have the filter changed while you are at it. It will be a bit of expense, but if the trans is in decent condition, it will be a long time before needing fluid in the future. What little oil remaining in the 'bowels' of the trans after being purged won't make any difference with the new fluid you install.
Safety Car
Joined: Jul 2005
Posts: 3,687
Likes: 833
From: WI
Some fluids have anti-shudder agents added to it, like Penzoil (my pick).
You probably can mix them ok if you're a little low at the moment. I've added fluid to vehicles I've bought ..and the world didn't stop. But best if you have it changed/flushed.
You probably can mix them ok if you're a little low at the moment. I've added fluid to vehicles I've bought ..and the world didn't stop. But best if you have it changed/flushed.
Thread Starter
Burning Brakes
Joined: Sep 2017
Posts: 1,069
Likes: 63
From: Belgium
Thread Starter
Burning Brakes
Joined: Sep 2017
Posts: 1,069
Likes: 63
From: Belgium
Thanks!
I bought about 15 L of ATF (Dexron III). Will do 'an almost complete flush' (can't flush the torque converter). + new filter and pan.
A flush like this (don't mind the title):
I bought about 15 L of ATF (Dexron III). Will do 'an almost complete flush' (can't flush the torque converter). + new filter and pan.
A flush like this (don't mind the title):
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Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
You can spin the convertor with the engine [idle speed] to get most of the fluid out of it once the rest has been drained. Do this AFTER draining the sump but BEFORE removing the sump pan, as you don't wantoil in the sump pan to re-fill the converter. Once the oil in the pan has been drained, just start engine at idle and let the out-flow from the convertor go into the sump to drain, also. You only need to run it at idle for 10-15 seconds and it will spin most of the oil out of the convertor.
hen you can drop the pan if you want to change the filter (which I would recommend doing, if it has been several years). Otherwise, just install the pan drain plug and refill with fluid; then start engine to get trans oil to circulate and fill more until at proper level.
hen you can drop the pan if you want to change the filter (which I would recommend doing, if it has been several years). Otherwise, just install the pan drain plug and refill with fluid; then start engine to get trans oil to circulate and fill more until at proper level.
Last edited by 7T1vette; Sep 23, 2020 at 03:59 PM.