Trans Fluid ?

[HotAirWH1]

Need to change the trans fluid. The fluid in there is not a synthetic and last replace sometime in the late 80's. Shall I stay with a non synthetic or can I use a synthetic since there will be some old fluid left in the torque converter.

 

[grass doctor]

most will recommend dex VI for stock applications, some will say type F , many, many , many opinions on this , I have read numerous threads on it with very little scientific or legitimate reasons to back their recommendations, but there are some good points made by some GL

 

[grass doctor]

you will not be able to get all of the old fluid out unless you take the torque converter off , but not a big deal full system capacity is 12 qts but unless you drain the TQ , you'll only need 8 or so quarts, now if your really picking about getting all of it out you can get 60/70 percent of the fluid out of the TQ without taking it off by raising nose up and let it drain over night then turn the motor 180 and let TQ drain then turn another 180 and drain some more, also recommended to disconnect the computer if doing this tedious method and can be messy

 

[HotAirWH1]

My intentions is to just do a simply trans-fusion. I don't want to drain the TQ. I'm assuming the fluid is most likely a Dextron II since Dextron III did not come onto the market until 1993. I have read that this fluid is backward compatible with all previous Dextron fluids. So, if this hold true, then a Dextron IV should be compatible to any of the earlier Dextron products. My initial question is it OK to use a synthetic if the fluid in the transmission is a non-synthetic. Maybe I'm overthinking this..... or just get a Dextron II since this is probably whats in it now and skip the synthetics. I would like to use the best product on the market (synthetics) but don't want to F**k things up.

 

[grass doctor]

synthetic and non synthetic ATF are compatible

 

[Hahny]

Type F gets my vote!!

 

[rodruckus]

I've been using Havoline MD-3 in my Art Carr 200-4R Extreme for years and tens of thousands of miles without issue. I also add a full bottle of Lucas Transmission Fix to it. Just like I add a quart of Lucas Heavy Duty Oil Stabilizer with my Brad Penn motor oil. Shit's been bullet-proof in both applications. And believe me, I torture test both.

There are other manufacturers who still produce Dex III, you'll just find it under a new name now, MD-3. Because of trademark reasons, they can no longer use the Mercon/Dex III name. I gravitate to Havoline, since I can no longer find Chevron brand. It basically is Chevron, since they're all part of the same company. I used Chevron prior on the same trans for close to a decade and tens of thousands of more miles. When I drop my pan between services, I only have a very small bit of metal on my magnetic drain plug and that's it. I guess I lucked out and got one of his good ones. It only took 3 tries, the first 2 burnt up real quick.

You can usually find Havoline at Rural King for a really good price.

 

[grass doctor]

type f is said to have firmer shifts

 

[Hahny]

type f is said to have firmer shifts

That is correct grass doctor. I have tired dex vi/ III and the type F gives the firmest shifts.

 

[KC87]

Dexron VI is supposed to be the replacement for all prior Dexron fluid. IIrc after a certain length of time GM won't certify the older ones or something like that (legal mumbo-jumbo) and they don't necessarily have to meet the old specs. Not saying the big name makers like Chevron would skimp but who knows about others that blend their own. Haven't seen Dex-3 for who knows how long.
And remember not to let anyone talk you into a transmission flush or you'll most likely get into a trans rebuild pretty soon after all this time.
Believe there's only 2 companies that make trans fluid, Chevron and Texaco iirc. Think the others smaller suppliers that add their own "special" so called additives to it.

 

[TexasT]

I'll slide this sideways. I have been using hydraulic fluid. Seems to work decent.

 

[grass doctor]

if had a 700 plus HP tranny id be using the John Deere HY Gard , heard and seen great things about it in high horsepower applications

 

[KC87]

if had a 700 plus HP tranny id be using the John Deere HY Gard , heard and seen great things about it in high horsepower applications

I don't know, putting something that looks like motor oil and isn't red in a Buick auto trans just seems wrong. lol. Like putting water in your scotch.

 

[TexasT]

The stuff I put in just looks like clear somewhat thick liquid. The motor oil I use has more of a Carmel color to it.

 

[Frederickdav]

Dexron VI is supposed to be the replacement for all prior Dexron fluid. IIrc after a certain length of time GM won't certify the older ones or something like that (legal mumbo-jumbo) and they don't necessarily have to meet the old specs. Not saying the big name makers like Chevron would skimp but who knows about others that blend their own. Haven't seen Dex-3 for who knows how long.
And remember not to let anyone talk you into a transmission flush or you'll most likely get into a trans rebuild pretty soon after all this time.
Believe there's only 2 companies that make trans fluid, Chevron and Texaco iirc. Think the others smaller suppliers that add their own "special" so called additives to it.

So, what's the problem with trans flush? I know that happens. It happened to my old 78 Pontiac when I had the trans flushed. A month or so later and the trans needed a rebuild. Just want to know what causes the problem?

 

[TexasT]

New trans fluid has detergents in it that "could" loosen up the crudge(technical term) in a "seasoned" trans. This "crudge" can get into areas including the vb that cause all kinds of havoc. The slipperyness(also a technical term) of the new fluid can also cause clutch materials to, well, slip. This slipping isn't good. The additives can also cause seals to shrink or expand letting pressure by and clutches to not be applied as needed.

I'm not saying not to change fluid and filter, just that with high mile units can suffer. If'n it ain't broke, fixing it until it is can result.

 

[HotAirWH1]

New trans fluid has detergents in it that "could" loosen up the crudge(technical term) in a "seasoned" trans. This "crudge" can get into areas including the vb that cause all kinds of havoc. The slipperyness(also a technical term) of the new fluid can also cause clutch materials to, well, slip. This slipping isn't good. The additives can also cause seals to shrink or expand letting pressure by and clutches to not be applied as needed.

I'm not saying not to change fluid and filter, just that with high mile units can suffer. If'n it ain't broke, fixing it until it is can result.

 

[IrvJr]

I have a T Tech trans flush machine in my garage, use it on all my vehicles and other peoples vehicles as well. The only one who had issues was someone who already had slipping issues. If your trans is unmaintained for decades its gonna fail regardless. If youre worried about crud loosening up then you should equally be concerned about where its built up and blocking passages before the flush. Either way, adding new fluid the detergent will loosen it up crud no matter which way you do it.

 

[grass doctor]

New trans fluid has detergents in it that "could" loosen up the crudge(technical term) in a "seasoned" trans. This "crudge" can get into areas including the vb that cause all kinds of havoc. The slipperyness(also a technical term) of the new fluid can also cause clutch materials to, well, slip. This slipping isn't good. The additives can also cause seals to shrink or expand letting pressure by and clutches to not be applied as needed.

I'm not saying not to change fluid and filter, just that with high mile units can suffer. If'n it ain't broke, fixing it until it is can result.

I guess its like a mattress you should change it every 8 years regardless of milage

 

[KC87]

The stuff I put in just looks like clear somewhat thick liquid. The motor oil I use has more of a Carmel color to it.

Oh, you're talking about a 7&7.