Opinions on Transmission Fluid Changes - The 1947 - Present Chevrolet & GMC Truck Message Board Network

SourTooth307 · 10-16-2014, 01:04 PM

The fluid in my 84 K/10's trans is dark and recently I've noticed a weak shift from 1st to 2nd under light throttle. I've been hearing some conflicting opinions on whether or not changing the fluid is good or bad. I have heard fluid FLUSHES are to be avoided, but I'm talking about a new pan gasket, new filter, and letting as much of the fluid that wants to drain out to drain out. Then replacing what came out with fresh fluid. Should I go ahead and do the trans service or is it best to be left alone to not ruin any existing seals inside the trans?

walkerb · 10-16-2014, 02:05 PM

I have always gotten different opinions also.

I would do what your planning on changing. Its sounds like its in need of something anyways. Do it and start looking for a replacement t350? or tranny shop, just incase.

rich weyand · 10-16-2014, 03:39 PM

Drain it, put in full synthetic ATF, and add a bottle of this stuff.
http://www.summitracing.com/parts/atp-at205

homemade87 · 10-16-2014, 07:22 PM

The reason you hear conflicting opinions is what happens when you change the fluid you take away the friction particles from the fluid that it is using the keep the clutches from slipping.The clutches are wore out. If you change the fluid it removes what it is using to keep the clutches from slipping. Thats why you hear of people changing the fluid and the trans no longer will shift or work. I would not change the fluid until you decide to get another or time your rebuild. Its only a matter of time. New fluid will not fix your problem. It will most likely make it worse.

**old Rusty C10** · 10-16-2014, 07:57 PM

I tend to agree with Homemade87.. if you regularly change the fluids since you put in a new trans every 24-30K you would be ok but once you start experiencing weak shifts or the fluid is burnt, you will only hasten the death of the trans

clinebarger · 10-16-2014, 08:47 PM

If it's a TH350, Drop the pan (Save the Fluid), If the pan is full of Mud, Clean the pan out, Replace Filter. Strain old ATF with a rag & refill...Top off with fresh fluid. Save up for a rebuild. No sense in leaving a filter in that is most likely clogged.

Let us know if you have a 700R4, Several things can cause a soft 1-2, 90% of them can be fixed without pulling the trans.

SourTooth307 · 10-17-2014, 11:49 AM

Quote:

Originally Posted by clinebarger

If it's a TH350, Drop the pan (Save the Fluid), If the pan is full of Mud, Clean the pan out, Replace Filter. Strain old ATF with a rag & refill...Top off with fresh fluid. Save up for a rebuild. No sense in leaving a filter in that is most likely clogged.

Let us know if you have a 700R4, Several things can cause a soft 1-2, 90% of them can be fixed without pulling the trans.

I'm pretty sure it's a 700R4, it's a 4-speed w/ overdrive. My 76 Cadillac had a THM350 and I remember it being a 3-speed.

Dead Parrot · 10-17-2014, 03:51 PM

I would plan on changing the fluid and filter. My guess is most failures that are blamed on fluid changes are due to the transmission finally failing due to neglect or just plain being wore out. On the other hand, not changing the fluid just continues the neglect problem.

Before doing anything, research the fixes clinebarger mentions as they may require dropping the pan anyway.

smashingchuck · 10-17-2014, 04:24 PM

Quote:

Originally Posted by homemade87

The reason you hear conflicting opinions is what happens when you change the fluid you take away the friction particles from the fluid that it is using the keep the clutches from slipping.The clutches are wore out. If you change the fluid it removes what it is using to keep the clutches from slipping. Thats why you hear of people changing the fluid and the trans no longer will shift or work. I would not change the fluid until you decide to get another or time your rebuild. Its only a matter of time. New fluid will not fix your problem. It will most likely make it worse.

^This. Speaking from experience, save your money for the rebuild. Changing the fluid will only compound your problems.

motornut · 10-17-2014, 04:27 PM

Quote:

Originally Posted by clinebarger

If it's a TH350, Drop the pan (Save the Fluid), If the pan is full of Mud, Clean the pan out, Replace Filter. Strain old ATF with a rag & refill...Top off with fresh fluid. Save up for a rebuild. No sense in leaving a filter in that is most likely clogged.

Let us know if you have a 700R4, Several things can cause a soft 1-2, 90% of them can be fixed without pulling the trans.

I've used auto paint filters to filter ATF used in my plow pistons.
hadn't thought of the tranny but I've replaced burnt fluid and filter that i could get out before,
but then no go.(got it rebuilt)
BTW (paint filters) work on cooled deep fryer grease too lol

clinebarger · 10-18-2014, 07:51 PM

Quote:

Originally Posted by SourTooth307

I'm pretty sure it's a 700R4, it's a 4-speed w/ overdrive. My 76 Cadillac had a THM350 and I remember it being a 3-speed.

Drop the pan, If there is a lot of Clutch debris or Metal, Time for a rebuild!
Unlike TH350/TH400....700R4's run clean until they are ready to fail.

If the pan is fairly clean, Check you TV cable adjustment (I have posted on this several times in the Engine & Drivetrain section).

If TV adjustment is OK, Remove the 1-2 Accumulator Housing, Check for a Broken Accumulator Spring, & Holes in the Separator Plate, Yes, The Spring can wear a hole right through the plate.

Sabaka454 · 10-19-2014, 09:41 AM

Fluid flushes are great if they are performed correctly and if you are using good product. Find a BG certified shop http://www.bgfindashop.com/locator/index.php

SourTooth307 · 10-20-2014, 03:32 PM

All right, I appreciate all the advice and opinions given here. I think I'm gonna go with what Clinebarger recommended and check for metal in the pan. I'll change the filter/pan gasket for fun and go from there. If it looks beat then I'll put the old fluid back in and just ride it out. What do you guys think, good plan?

Koffer · 10-20-2014, 04:28 PM

Quote:

Originally Posted by SourTooth307

All right, I appreciate all the advice and opinions given here. I think I'm gonna go with what Clinebarger recommended and check for metal in the pan. I'll change the filter/pan gasket for fun and go from there. If it looks beat then I'll put the old fluid back in and just ride it out. What do you guys think, good plan?

Sounds good to me , Clinebarger helped me get a700r4 installed and all setup correctly in my 77 P10 with a 292 6 . He's not going to steer you in the wrong direction with what to do

SourTooth307 · 10-20-2014, 11:10 PM

Quote:

Originally Posted by Koffer

Sounds good to me , Clinebarger helped me get a700r4 installed and all setup correctly in my 77 P10 with a 292 6 . He's not going to steer you in the wrong direction with what to do

Everyone on here gave great opinions and insight to what my problem could be and how to deal with it. Clinebarger's info happened to encompass the best of both anti-fluid change and pro-fluid change specific to what trans I have so I liked what he said. I'm all too familiar with TV cable maladjustment having dealt with that on my Fleetwood Brougham's 307+200R4 combo.....

LostMy65 · 12-12-2015, 05:14 PM

I have a Summit Th350 with very little miles I bought from another. I dropped the pan to install a Lokar Dipstick. The fluid is nice fresh and clean. The only problem is I don't know what kind of fluid to put back in it.
It still has fluid in the Torque Converter, so I guess my concern is if it matters that whatever is in it needs to be the same or not?

foamypirate · 12-12-2015, 06:48 PM

Quote:

Originally Posted by LostMy65

I have a Summit Th350 with very little miles I bought from another. I dropped the pan to install a Lokar Dipstick. The fluid is nice fresh and clean. The only problem is I don't know what kind of fluid to put back in it.
It still has fluid in the Torque Converter, so I guess my concern is if it matters that whatever is in it needs to be the same or not?

Anything Dexron III certified will be fine.

LostMy65 · 12-12-2015, 08:41 PM

I see there is different Types such as Type F.
What Type should I use?

**hatzie** · 12-12-2015, 09:18 PM

For the TH700R4 TH400 TH350 4L60 4L80 3L60 or 3L80 in good condition fill with Dexron VI.
There is no such thing as Dexron III certified anymore. In 2006 GM stopped buying and licensing it so there's no guarantee it's Dexron III anymore because the fox is watching the henhouse.

Here's GM Tech Service Bulletin 04-07-30-037D on the "new" Dexron VI transmission fluid. Our trucks fall into the "2008 and Prior GM Passenger Cars and Light Duty Trucks" category...
It's worth reading the recommendation to not use Dexron VI in Power Steering, Manual Transmissions, and Transfer cases that originally called for Dexron III. It obviously doesn't apply to the SM465 or the NP203 & NP205 transfer cases that had other fluid recommendations.
The GM recommended juice is noticeably less expensive than the Exxon Mobil product I would trust.

"The content of this bulletin does not apply to manual transmissions or transfer cases. Any
vehicle that previously required DEXRON®-III for a manual transmission or transfer case
should now use P/N 88861800. This fluid is labeled Manual Transmission and Transfer Case
Fluid. Power Steering Systems should now use P/N 9985010 labeled Power Steering Fluid."

foamypirate · 12-12-2015, 09:35 PM

Quote:

Originally Posted by hatzie

For a TH700R4 in good condition fill with Dexron VI.
There is no such thing as Dexron III anymore. It's been gone since 2006 when GM stopped buying and licensing it.

Here's GM Tech Service Bulletin 04-07-30-037D on the "new" Dexron VI transmission fluid. Our trucks fall into the "2008 and Prior GM Passenger Cars and Light Duty Trucks" category...
It's worth reading the recommendation to not use Dexron VI in Power Steering, Manual Transmissions, and Transfer cases that originally called for Dexron III.

"The content of this bulletin does not apply to manual transmissions or transfer cases. Any
vehicle that previously required DEXRON®-III for a manual transmission or transfer case
should now use P/N 88861800. This fluid is labeled Manual Transmission and Transfer Case
Fluid. Power Steering Systems should now use P/N 9985010 labeled Power Steering Fluid."

Dexron VI is expensive, and in my opinion, a complete waste to run in a 700R4 or an TH350/TH400.

Something that says it's suitable to use in a transmission that called for Dexron III originally will be perfectly fine and acceptable, even Wal-Mart Supertech. Heck, even a lot of the big name trans guys have no qualms with Supertech. There is no need to spend the big bucks on Dexron VI unless you are running a late model trans, in my book. You can get a gallon of Dexron III compatible Supertech for $15 or so. I've been running it in my GM autos for years without a single problem.

Liberty · 12-12-2015, 09:45 PM

My transmission guy said the fluid type doesn't really matter, the main difference he said was some fluids grip differently. He always ran Ford fluid in his GMs to make them shift harder. The GM fluid allows some slippage for smoother shifts.

That being said I just run Dexron whatever from AutoZone.

**hatzie** · 12-13-2015, 09:37 AM

Quote:

Originally Posted by foamypirate

Dexron VI is expensive, and in my opinion, a complete waste to run in a 700R4 or an TH350/TH400.

Something that says it's suitable to use in a transmission that called for Dexron III originally will be perfectly fine and acceptable, even Wal-Mart Supertech. Heck, even a lot of the big name trans guys have no qualms with Supertech. There is no need to spend the big bucks on Dexron VI unless you are running a late model trans, in my book. You can get a gallon of Dexron III compatible Supertech for $15 or so. I've been running it in my GM autos for years without a single problem.

UMMM... NO. Not more expensive. Exactly the same price.
http://www.walmart.com/browse/auto-t...d:Super%20Tech
The WalMart Supertech Dexron VI is licensed just like everything labeled Dexron VI. It's the same $4.27/qt as the Multi-Vehicle Dexron Mercon. Super expensive stuff there.

foamypirate · 12-13-2015, 11:12 AM

Quote:

Originally Posted by hatzie

UMMM... NO. Not more expensive. Exactly the same price.
http://www.walmart.com/browse/auto-t...d:Super%20Tech
The WalMart Supertech Dexron VI is licensed just like everything labeled Dexron VI. It's the same $4.27/qt as the Multi-Vehicle Dexron Mercon. Super expensive stuff there.

Fair enough, it's been a few years since I looked at dex vi. Used to be a lot more expensive.
Posted via Mobile Device

**hatzie** · 12-13-2015, 11:59 AM

A lot more GM rigs on the road that came with Dexron VI now. Demand is up so supply is up and price is down. The inverse is true of Dexron III.
Dexron III compatible price isn't likely to stay even with Dexron VI for much longer.

barry1982 · 12-31-2015, 12:40 AM

I have always changed/flushed auto trans oil in my own shop. I pull the pan, change filter and reinstall. Pour in a gallon of new ATF, and remove the lower trans line from radiator. I than slide a short piece of rubber hose on line , and put into drain pail. Start the truck, and let fluid pump from line into pail until clean , red fluid appears. Reinstall line on rad, and refill trans to correct level. Maybe not quite as effective as a professional flush, but works and saves you a few bucks.

10-16-2014, 01:04 PM	#1
SourTooth307 Registered User Join Date: Feb 2014 Location: Lodi, NJ Posts: 166	Opinions on Transmission Fluid Changes The fluid in my 84 K/10's trans is dark and recently I've noticed a weak shift from 1st to 2nd under light throttle. I've been hearing some conflicting opinions on whether or not changing the fluid is good or bad. I have heard fluid FLUSHES are to be avoided, but I'm talking about a new pan gasket, new filter, and letting as much of the fluid that wants to drain out to drain out. Then replacing what came out with fresh fluid. Should I go ahead and do the trans service or is it best to be left alone to not ruin any existing seals inside the trans? __________________ My Wheels: 1984 Chevrolet K/10 Scottsdale 350cid SOLD 1989 Cadillac Fleetwood Brougham d'Elegance 307cid 2015 Chevrolet Silverado 1500 LT Texas Edition 5.3L 4x4

10-16-2014, 02:05 PM	#2
walkerb Registered User Join Date: May 2010 Location: Rochester NY Posts: 831	Re: Opinions on Transmission Fluid Changes I have always gotten different opinions also. I would do what your planning on changing. Its sounds like its in need of something anyways. Do it and start looking for a replacement t350? or tranny shop, just incase. __________________ 1973 k20 Suburban 350 1974 Custom stepside c-10 250 1975 Chevy stepside 454 1986 K30 Crewcab SRW 350 R.I.P- glimmertwin01- board member and good friend, you will be missed

10-16-2014, 03:39 PM	#3
rich weyand Registered User Join Date: Apr 2014 Location: Bloomington Indiana Posts: 1,041	Re: Opinions on Transmission Fluid Changes Drain it, put in full synthetic ATF, and add a bottle of this stuff. http://www.summitracing.com/parts/atp-at205 __________________ Rich Weyand 1978 K10 RCSB DD.

10-16-2014, 07:22 PM	#4
homemade87 Registered User Join Date: Apr 2010 Location: Guntersville Alabama Posts: 1,073	Re: Opinions on Transmission Fluid Changes The reason you hear conflicting opinions is what happens when you change the fluid you take away the friction particles from the fluid that it is using the keep the clutches from slipping.The clutches are wore out. If you change the fluid it removes what it is using to keep the clutches from slipping. Thats why you hear of people changing the fluid and the trans no longer will shift or work. I would not change the fluid until you decide to get another or time your rebuild. Its only a matter of time. New fluid will not fix your problem. It will most likely make it worse.

10-16-2014, 07:57 PM	#5
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,316	Re: Opinions on Transmission Fluid Changes I tend to agree with Homemade87.. if you regularly change the fluids since you put in a new trans every 24-30K you would be ok but once you start experiencing weak shifts or the fluid is burnt, you will only hasten the death of the trans __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

10-16-2014, 08:47 PM	#6
clinebarger Senior Member Join Date: May 2009 Location: Fort Worth, TX Posts: 6,370	Re: Opinions on Transmission Fluid Changes If it's a TH350, Drop the pan (Save the Fluid), If the pan is full of Mud, Clean the pan out, Replace Filter. Strain old ATF with a rag & refill...Top off with fresh fluid. Save up for a rebuild. No sense in leaving a filter in that is most likely clogged. Let us know if you have a 700R4, Several things can cause a soft 1-2, 90% of them can be fixed without pulling the trans.

10-17-2014, 03:51 PM	#8
Dead Parrot Registered User Join Date: Aug 2012 Location: Oklahoma City, OK Posts: 2,629	Re: Opinions on Transmission Fluid Changes I would plan on changing the fluid and filter. My guess is most failures that are blamed on fluid changes are due to the transmission finally failing due to neglect or just plain being wore out. On the other hand, not changing the fluid just continues the neglect problem. Before doing anything, research the fixes clinebarger mentions as they may require dropping the pan anyway.

10-19-2014, 09:41 AM	#12
Sabaka454 Registered User Join Date: Jul 2005 Location: CT Posts: 278	Re: Opinions on Transmission Fluid Changes Fluid flushes are great if they are performed correctly and if you are using good product. Find a BG certified shop http://www.bgfindashop.com/locator/index.php

10-20-2014, 03:32 PM	#13
SourTooth307 Registered User Join Date: Feb 2014 Location: Lodi, NJ Posts: 166	Re: Opinions on Transmission Fluid Changes All right, I appreciate all the advice and opinions given here. I think I'm gonna go with what Clinebarger recommended and check for metal in the pan. I'll change the filter/pan gasket for fun and go from there. If it looks beat then I'll put the old fluid back in and just ride it out. What do you guys think, good plan? __________________ My Wheels: 1984 Chevrolet K/10 Scottsdale 350cid SOLD 1989 Cadillac Fleetwood Brougham d'Elegance 307cid 2015 Chevrolet Silverado 1500 LT Texas Edition 5.3L 4x4

12-12-2015, 05:14 PM	#16
LostMy65 But Found Her 25yrs Later! Join Date: Oct 2010 Location: Oregon City, Oregon Posts: 10,530	Re: Opinions on Transmission Fluid Changes I have a Summit Th350 with very little miles I bought from another. I dropped the pan to install a Lokar Dipstick. The fluid is nice fresh and clean. The only problem is I don't know what kind of fluid to put back in it. It still has fluid in the Torque Converter, so I guess my concern is if it matters that whatever is in it needs to be the same or not? __________________ I lost my 65 - Found it 25 years later: http://67-72chevytrucks.com/vboard/s...d.php?t=426650 66 C20 Service Truck: http://67-72chevytrucks.com/vboard/s...d.php?t=428035

12-12-2015, 08:41 PM	#18
LostMy65 But Found Her 25yrs Later! Join Date: Oct 2010 Location: Oregon City, Oregon Posts: 10,530	Re: Opinions on Transmission Fluid Changes I see there is different Types such as Type F. What Type should I use? __________________ I lost my 65 - Found it 25 years later: http://67-72chevytrucks.com/vboard/s...d.php?t=426650 66 C20 Service Truck: http://67-72chevytrucks.com/vboard/s...d.php?t=428035

12-12-2015, 09:18 PM	#19
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 5,014	Re: Opinions on Transmission Fluid Changes For the TH700R4 TH400 TH350 4L60 4L80 3L60 or 3L80 in good condition fill with Dexron VI. There is no such thing as Dexron III certified anymore. In 2006 GM stopped buying and licensing it so there's no guarantee it's Dexron III anymore because the fox is watching the henhouse. Here's GM Tech Service Bulletin 04-07-30-037D on the "new" Dexron VI transmission fluid. Our trucks fall into the "2008 and Prior GM Passenger Cars and Light Duty Trucks" category... It's worth reading the recommendation to not use Dexron VI in Power Steering, Manual Transmissions, and Transfer cases that originally called for Dexron III. It obviously doesn't apply to the SM465 or the NP203 & NP205 transfer cases that had other fluid recommendations. The GM recommended juice is noticeably less expensive than the Exxon Mobil product I would trust. "The content of this bulletin does not apply to manual transmissions or transfer cases. Any vehicle that previously required DEXRON®-III for a manual transmission or transfer case should now use P/N 88861800. This fluid is labeled Manual Transmission and Transfer Case Fluid. Power Steering Systems should now use P/N 9985010 labeled Power Steering Fluid." __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful. Last edited by hatzie; 12-12-2015 at 09:33 PM.

12-12-2015, 09:45 PM	#21
Liberty Registered User Join Date: Feb 2015 Location: Bonham, Texas Posts: 241	Re: Opinions on Transmission Fluid Changes My transmission guy said the fluid type doesn't really matter, the main difference he said was some fluids grip differently. He always ran Ford fluid in his GMs to make them shift harder. The GM fluid allows some slippage for smoother shifts. That being said I just run Dexron whatever from AutoZone.

12-13-2015, 11:59 AM	#24
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 5,014	Re: Opinions on Transmission Fluid Changes A lot more GM rigs on the road that came with Dexron VI now. Demand is up so supply is up and price is down. The inverse is true of Dexron III. Dexron III compatible price isn't likely to stay even with Dexron VI for much longer. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

12-31-2015, 12:40 AM	#25
barry1982 Registered User Join Date: Oct 2015 Location: Waskatenau, Alberta Posts: 259	Re: Opinions on Transmission Fluid Changes I have always changed/flushed auto trans oil in my own shop. I pull the pan, change filter and reinstall. Pour in a gallon of new ATF, and remove the lower trans line from radiator. I than slide a short piece of rubber hose on line , and put into drain pail. Start the truck, and let fluid pump from line into pail until clean , red fluid appears. Reinstall line on rad, and refill trans to correct level. Maybe not quite as effective as a professional flush, but works and saves you a few bucks.



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