Quick Newbie Question

[CeviL]

Just recently picked up a 90 k5 silverado, 350/700r4 with 193 on the dash. Appears to be all orig.

Was wondering if someone could point me in the right direction of two simple questions due to the fact that I'm having trouble logging into mitchell online atm.

1) I'm doing a transmission oil change on the 700r4 and need to know how many quarts I'm going to need. Again appears all orig and stock pan.

&

2) For having 193XXX and god knows when the kid last changed it, what fluid would hold the popular consensus for most recommended type/brand/specialty?

Thanks in advance,
Jon

 

[Greg72]

I will give you one word of caution....

On high-mileage transmissions it is not uncommon for a new, eager owner such as yourself to flush out all that "bad" transmission fluid only to experience a complete transmission failure within a few thousand miles afterwards.

It doesn't make a lot of sense at first, but the reality is that the worn clutch material floating around in that bad fluid is actually providing valuable friction for the worn clutches. Once that is all rinsed away, the clutches will slip and burn pretty fast.

Maybe someone else will have different advice, but if it were me I wouldn't flush out that fluid unless I already had the money put aside for a complete transmission rebuild (just in case)!!!

 

[CeviL]

Thank you for your advice and concern. I am very aware of problems such as that of the tranny going south after this flush. However, I do have another 700r4 transmission out of a 87 suburban sitting in my garage I just rebuilt last winter in case of such a disaster.

 

[wasted wages]

I will give you one word of caution....

On high-mileage transmissions it is not uncommon for a new, eager owner such as yourself to flush out all that "bad" transmission fluid only to experience a complete transmission failure within a few thousand miles afterwards.

It doesn't make a lot of sense at first, but the reality is that the worn clutch material floating around in that bad fluid is actually providing valuable friction for the worn clutches. Once that is all rinsed away, the clutches will slip and burn pretty fast.

Maybe someone else will have different advice, but if it were me I wouldn't flush out that fluid unless I already had the money put aside for a complete transmission rebuild (just in case)!!!

excellent advice....

I have had good luck with the new synthetics that are universal for use in most transmissions now....type F ,,dextron,,dextron 2...

 

[Fred_M1010]

I believe dexron 3 is the recommended fluid for a TH700r4
What brand to use, and synthetic or not is a matter of personal taste.
I think it's more important to change it often than it is to use expensive fluids.

That thing about clutch debris keeping a transmission alive sounds like an urban myth to me...
I think the benefits of clean and fresh oil would outweigh it.

 

[tRustyK5]

It's no myth, and it's happened to plenty of guys here including Can Can. He had the big flush done on a 700R-4 with 140,000 or so on it. Fluid color was normal, never had any issues with it, shifted firmly. 2000 miles after the flush it was fried and he needed to have it rebuilt. A straight fluid and filter change is usually OK, it's when you do the whole flush thing that can lead to tranny death for a high mile 700R-4.

My 700 has 230,000 on it, and I will not flush it. At this point in it's life about all I'm gonna do is add fluid if it needs it.

Rene

 

[cardoff_giant]

It happend to me last year.

IIRC put one quart in the torque converter and 10 in the transmission. We put one in the torque and about 7 in the transmission and then started putting it into gear. No movement, forward or back, just slide the shifter to let that oil go where it needs to. Then add one quart at a time and use the feel of the shifter and the dip stick to get it dead on.


Good Luck.

 

[mikkelsent9584]

I will give you one word of caution....

On high-mileage transmissions it is not uncommon for a new, eager owner such as yourself to flush out all that "bad" transmission fluid only to experience a complete transmission failure within a few thousand miles afterwards.

It doesn't make a lot of sense at first, but the reality is that the worn clutch material floating around in that bad fluid is actually providing valuable friction for the worn clutches. Once that is all rinsed away, the clutches will slip and burn pretty fast.

Maybe someone else will have different advice, but if it were me I wouldn't flush out that fluid unless I already had the money put aside for a complete transmission rebuild (just in case)!!!

I had this happen to me. I bought a 1989 Blazer with 93,000 on it all original. With service documents to back up the mileage. And it was a family friend. I took it to get flushed so i could drive it back home. It made it 150 miles headed home then it was TOAST! $900 later i have a new 700r4.

Great advice!! He is right!

 

[midnitewarya]

Same thing happened to me at 90K. Had a 1000 mile drive coming up and decided a flush would be good. 70 miles down the road I hear horrible noises and the tranny fluid is all over the back window. $900 later it was fixed. The tranny I have now has 180,000+ and has been beaten and bashed. I will never flush the fluid, only add as needed.

700s are strang creatures.

This whole topic reminds me of an episode of Powerblock on Spike. They got hold of an old Toyota and dynoed it. Then they changed the distributer, coil, wires and plugs. Dynoed again and it had less power.

 

[Fordum]

Greg72 is close. The friction material mostly stays at the bottom of the pan and in the filter.
What happens is, automatic transmission fluid has great solvent and cleaning properties.
But, like any cleaner, it reaches a point where it has dissolved and removed all the wear particles it can hold in suspension.
Its basically saturated.
So, as things continue to wear, the crud builds up in the tight places. Gradually replacing seals, and other things.

Then, when you replace the oil, the new oil starts cleaning everything up.
This does two things.
One, it causes the seals which were sealing against crud to start leaking.
Two, it can cause so much junk to dissolve out at one time that it clogs up control passages

Either way, the transmission stops working.

The transmission on my truck has about 240,000 miles on it, and I would not hesitate to change the fluid in it.
But, the fluid has been changed once per year since I got it.

J.

 

[bailey9r]

X2 on the cleaning doing the damage, if it hasn't been serviced in 50 k just leave it alone other than adding when needed

 

[Greg72]

Greg72 is close. The friction material mostly stays at the bottom of the pan and in the filter.
What happens is, automatic transmission fluid has great solvent and cleaning properties.
But, like any cleaner, it reaches a point where it has dissolved and removed all the wear particles it can hold in suspension.
Its basically saturated.
So, as things continue to wear, the crud builds up in the tight places. Gradually replacing seals, and other things.

Then, when you replace the oil, the new oil starts cleaning everything up.
This does two things.
One, it causes the seals which were sealing against crud to start leaking.
Two, it can cause so much junk to dissolve out at one time that it clogs up control passages

Either way, the transmission stops working.

The transmission on my truck has about 240,000 miles on it, and I would not hesitate to change the fluid in it.
But, the fluid has been changed once per year since I got it.

J.

Good explanation! Seems to make good sense, especially to explain why transmissions with new fluid sometimes just puke out all the new fluid almost instantly.

Personally, if I had an "extra" rebuilt transmission already sitting in the garage I'd swap it in now....why wait to get stranded as the motivation to replace a tired old 700R4??