Auto Trans Fluid
Thread Starter
Heel & Toe
Joined: Jul 2015
Posts: 17
Likes: 0
Auto Trans Fluid
Hey guys I'm interested to hear your opinions...what transmission fluid would be ideal for my automatic 1985...I don't plan on racing or any extreme driving...just a daily driver I'm fixing up...is there some that stays good longer? The stuff in it now is just crap so I'm draining it and replacing it with new fluids...just getting an idea of what works well for you guys...high quality, low quality, what you guys prefer...fill me in on whatever you guys know
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Can you define "crap"?? 
Is the fluid a dark brown color? Does it have a burnt smell to it? Are there any signs of very fine particles in it?
How many miles on the car? Do you know if the trans is original to the car?
I would start by having a service done on the trans. This would be removal of the pan, replacing the filter, cleaning out the pan a re-install, and filling the trans back up. If the fluid seems to be really bad, have a reputable shop do a complete flush of the old fluid and a filter. Some say that this can shorten the life of the trans, but for daily driving, you should be OK.
GM auto trans of that era use a Dexron III fluid. That fluid is available at any parts store. Valvoline, Pennzoil, Mobil, Havoline, are all decent fluids for street use. I would not recommend a synthetic fluid; just regular Dex III.
Is the fluid a dark brown color? Does it have a burnt smell to it? Are there any signs of very fine particles in it?How many miles on the car? Do you know if the trans is original to the car?
I would start by having a service done on the trans. This would be removal of the pan, replacing the filter, cleaning out the pan a re-install, and filling the trans back up. If the fluid seems to be really bad, have a reputable shop do a complete flush of the old fluid and a filter. Some say that this can shorten the life of the trans, but for daily driving, you should be OK.
GM auto trans of that era use a Dexron III fluid. That fluid is available at any parts store. Valvoline, Pennzoil, Mobil, Havoline, are all decent fluids for street use. I would not recommend a synthetic fluid; just regular Dex III.
Thread Starter
Heel & Toe
Joined: Jul 2015
Posts: 17
Likes: 0
Auto Trans Fluid
Well thanks...super helpful...I believe the transmission is the original and it has 78k on it...idk what's in there now but it doesn't smell like Trans fluid...my friend even said he could barely tell what it was...I don't know if it just got stuff in it or if it was a certain brand or what...but I'll look into what you said...thanks again...
Safety Car
Joined: Aug 2009
Posts: 3,751
Likes: 276
From: Melbourne, Victoria, Australia
Hi
The (best thing) for an auto trans is a large trans cooler, just replace the dextron trans fluid with fresh fluid and fit a air cooled trans cooler.
That will extend the life of a transmission heat kills them.
Just cut one of the cooler lines to the radiator and either run through radiator and cooler, or just the external trans cooler.
Cheers
Gerard
The (best thing) for an auto trans is a large trans cooler, just replace the dextron trans fluid with fresh fluid and fit a air cooled trans cooler.
That will extend the life of a transmission heat kills them.
Just cut one of the cooler lines to the radiator and either run through radiator and cooler, or just the external trans cooler.
Cheers
Gerard
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
I'd likely not be concerned with adding a cooler at this point. It's maybe "pointless". I believe I'd do just a dump, filter and fill first. Cut the filter apart and inspect the trash in the pan when you do the dump. Depending on the color and smell of the fluid I'd likely just follow up that dump with another in a couple/few thousand miles with another filter (maybe) depending on what you find. I might consider two magnets when doing the service, both new.
I believe the expense of the flush professionally is maybe overkill for something that you already maybe question. Just use an off the shelf DEX/MERC that's suggested for early GM.
Two dumps should get you a relatively fresh fluid concentration. I've a friend who would insist on 1/2 bottle of Lucas conditioner if there's 80K with no previous records of service. I don't, but mine get serviced regularly. Lucas has two products FIX and CONDITIONER - use the conditioner not the FIX.
I believe the expense of the flush professionally is maybe overkill for something that you already maybe question. Just use an off the shelf DEX/MERC that's suggested for early GM.
Two dumps should get you a relatively fresh fluid concentration. I've a friend who would insist on 1/2 bottle of Lucas conditioner if there's 80K with no previous records of service. I don't, but mine get serviced regularly. Lucas has two products FIX and CONDITIONER - use the conditioner not the FIX.
Last edited by WVZR-1; Jul 16, 2015 at 09:48 PM.
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 113
From: Michigan
One of the things I did when I got my 86 was change the complete fluid, filter, pan and add a cooler. I used dex VI, because supposedly all dex III is not licensed these days and they have no control standard. Dex VI is backwards compatible and I used it in my th350 when I only changed the pan and filter, so it mixed with the rest of the fluid on that car. Also make sure the dex VI is licensed, I saw a list once and google prob can find it. From my research awhile back I herd that the dex VI is held to such a tight standard, brand really doesn't matter.
No big name brand or synthetic will fix worn or broken parts and if your trans isn't right don't waste the $.
No big name brand or synthetic will fix worn or broken parts and if your trans isn't right don't waste the $.
