What trans fluid should I use?
10-30-2013, 07:36 PM
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What trans fluid should I use? I have 50k on my car and I've had it for about 3 months so I decided to change the trans fluid out with Dexron VI, I figured it was backwards compatible and didn't give it much thought. After the flush It seemed to shift better than what was in there, but then I seen some posts on here and decided to change it back after around 500 miles to Valvoline Dexron III in fear of messing something up. Now it doesn't shift as well and I'm not sure if it's because its colder out or the fluid sucks. The owners manual says Dexron-III as does the side of the trans. What's your guys thoughts?
10-30-2013, 07:57 PM
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https://ls1tech.com/forums/cadillac-...sh-anyone.html
Post 5 (fuzzy) it's 3 quarts Redline D4 ATF and 1 quart Redline MTL 70W80 GL-4
I have used it with no problem, tranns shifts great 110k
As far as the dex3 or dex6 I'm pretty sure GMC doesn't use 3 anymore so everything uses 6 which will work with no problem and is backwards compatible. I would use the above redline though
Post 5 (fuzzy) it's 3 quarts Redline D4 ATF and 1 quart Redline MTL 70W80 GL-4
I have used it with no problem, tranns shifts great 110k
As far as the dex3 or dex6 I'm pretty sure GMC doesn't use 3 anymore so everything uses 6 which will work with no problem and is backwards compatible. I would use the above redline though
10-30-2013, 08:13 PM
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The gear oil is kind of concerning, this is from the Tremec site:
A hypoid gear oil by design does not allow mechanical surfaces to make contact with one another. A synchronizer relies on friction (much like your car's brakes) to do its job. Thus, gear oil in a synchronized transmission can be a bad combination, potentially causing a variety of shift quality issues. Furthermore, many gear oils contain sulfur additives that can damage friction materials.
A hypoid gear oil by design does not allow mechanical surfaces to make contact with one another. A synchronizer relies on friction (much like your car's brakes) to do its job. Thus, gear oil in a synchronized transmission can be a bad combination, potentially causing a variety of shift quality issues. Furthermore, many gear oils contain sulfur additives that can damage friction materials.
10-30-2013, 08:17 PM
#5
The most optimal mixture is 3 quarts Redline D4 ATF + 1 quart Redline MTL 70W80. You can go as high as 50/50 if your transmission is really old and/or battered, but you're going to experience some additional parasitic losses due to the thicker mixture.
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10-30-2013, 08:33 PM
#8
If you put Mobil 1 ATF in your transmission, it'll sound like a rock grinder and shift like one. Ask me how I know.
The most optimal mixture is 3 quarts Redline D4 ATF + 1 quart Redline MTL 70W80. You can go as high as 50/50 if your transmission is really old and/or battered, but you're going to experience some additional parasitic losses due to the thicker mixture.
The most optimal mixture is 3 quarts Redline D4 ATF + 1 quart Redline MTL 70W80. You can go as high as 50/50 if your transmission is really old and/or battered, but you're going to experience some additional parasitic losses due to the thicker mixture.
10-30-2013, 08:38 PM
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I run what the sticker on the side told me to. Shifts like I believe it should. I do live in Ca and the car sits in a garage so there is not the extreme temp shift as some states.
10-30-2013, 08:55 PM
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I run Mobil 1 and have for almost 60k. I now have over 155k on the car and still shifts great with no rock grinder noise. I have been wanting to change to amsoil torque drive that others have mentioned.
10-30-2013, 09:25 PM
#11
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I've tried almost everything from the Tremec recommended base Havoline DEX-III, to Mobil 1, and finally syncromesh. Royal Purple ATF will eat the friction lining from the syncro's.
In my opinion, Mobile 1 was the absolute worst by far. Syncromesh is pretty awful when cold (and the colder it is, the worse it is) but gets much better when hot, with a better overall feel than standard DEX-III. I now have a custom built T-56 Magnum and the builder supplied syncromesh with the trans...they won't warranty the unit without it.
Too many people have reported great success with the RedLine concoction for me to not try it myself, and will be next on the list after I get everything else in order. I have a friend who works at the largest BMW dealer in the area and he commented the same RedLine 75/25 or 50/50 mix has been used as an upgrade for a long time now, so I guess this is not a new thing.
In my opinion, Mobile 1 was the absolute worst by far. Syncromesh is pretty awful when cold (and the colder it is, the worse it is) but gets much better when hot, with a better overall feel than standard DEX-III. I now have a custom built T-56 Magnum and the builder supplied syncromesh with the trans...they won't warranty the unit without it.
Too many people have reported great success with the RedLine concoction for me to not try it myself, and will be next on the list after I get everything else in order. I have a friend who works at the largest BMW dealer in the area and he commented the same RedLine 75/25 or 50/50 mix has been used as an upgrade for a long time now, so I guess this is not a new thing.
10-30-2013, 09:32 PM
#13
How is Mobil 1 the worst if RP actually eats the friction lining on the synchros?
As a side note, I'm looking at Royal Purple's site and their Synchromax fluid states "Synchromax is recommended for manual transmissions that specify an automatic transmission fluid." I'm not saying anyone should try it, but it sounds like it could potentially be better than their ATF for our trans.
As a side note, I'm looking at Royal Purple's site and their Synchromax fluid states "Synchromax is recommended for manual transmissions that specify an automatic transmission fluid." I'm not saying anyone should try it, but it sounds like it could potentially be better than their ATF for our trans.
Last edited by bmylez; 10-30-2013 at 09:44 PM.
10-31-2013, 12:16 PM
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I've used Mobil 1 ATF , Royal Purple Max ATF Dexron III, and the Redline DF4 + MTL 70W80 GL-4 combo.
I'm currently running the Redline combo and I like it best out of the three.
I'm currently running the Redline combo and I like it best out of the three.
10-31-2013, 07:46 PM
#15
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I'm running the D4 ATF straight.
When I drained out the old fluid, it had the viscosity of water lol
Oils are just like anything else, you've get the same number of horror stories as you will success stories with one or another.
When I drained out the old fluid, it had the viscosity of water lol
Oils are just like anything else, you've get the same number of horror stories as you will success stories with one or another.
10-31-2013, 09:44 PM
#17
Do what fuzzy said! I promise you, you will be amazed at the difference. Before his mix I ran mobil one for 2,000 miles, terrible. Then did royal purple syncro mesh for 3,000 or so miles with some improvement. Then put in fuzzy's mix.....NIGHT. AND. DAY.
