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When to change old fluids? (E.g., PS, tranny, etc.)


wws944
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Could have posted this in the Reatta forum, but may be of more general interest.

 

My '90 Reatta only has 17K miles.  Of course the engine oil/filter and coolant have been replaced fairly recently.  Also brake fluid was done a while back.  But tranny and PS fluid are still 'factory fill' from 31 years ago.

 

So how often should one change these 'other' fluids in cars that are infrequently driven?

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Believe it or not manufacturers consider that "severe service" and recommend more frequent fluid changes.

 

My thought is if things are functioning correctly with no leaks, and the fluids are clean with no odd smell, you're good to go until normal service mileage intervals.

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26 minutes ago, rocketraider said:

Believe it or not manufacturers consider that "severe service" and recommend more frequent fluid changes.

 

My thought is if things are functioning correctly with no leaks, and the fluids are clean with no odd smell, you're good to go until normal service mileage intervals.

 

It seems like most recommendations in the manuals are based on mileage - and not time.  Coolant and maybe engine oil being the exception.

 

GM doesn't provide any recommendations at all for PS or brake fluid.  I guess if one considers 15 years to be the average life of a car, then the factory fill can be  "good for the life of the car".  But many folks here own cars that are several sigmas off the side of the bell curve...

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Trans fluid and power steering fluid are both likely Dexron II or 3.  If it's bright red it's like just fine.  If it's pale red to brownish it's got water in it or has been hot.

 

My cousin inherited my grandfather's last car, a 1955 Chevy BelAir back in the 70's.  When Grandpa died it was parked out in a back corner of my uncle's property in Farmington Hills, MI where it sat for over a year before my cousin decided to do something about it.  H thought since it was out in the weeds anyway he would drain and replace the engine oil.  He reported he was a little skeptical about the health of the engine after removing the oil pan plug and nothing happened..   Not to worry, after he poked a screwdriver through the layer of sludge in the bottom of the oil pan a few quarts of crude fell out of the pan.   He finished up his oil change and got the thing started and it smoked for awhile but he drove it for a few years before it quit.

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Drop your trans pan and do as thorough an oil change as possible. New filter, the best available. Refill with  modern synthetic ATF equivalent. Give Amsoil and/or Mobil a call and see what they recommend for your needs. Automatics  running synthetic ATF last forever.    -    Carl 

Edited by C Carl (see edit history)
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Anyone hear the old mechanic wife's tale that changing the auto trans fluid on a high mileage AT is likely to cause problems?  Something about the new fluid loosening up deposits....  I didn't let it stop me from changing it on the few cars I've owned in that category and experienced no problems.

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Just (re-)watched Prof Kellys video on the history of ATF at GM.  Factory fill in 1990 seems have been Dexron II(D):
 

 

21 minutes ago, MikeC5 said:

Anyone hear the old mechanic wife's tale that changing the auto trans fluid on a high mileage AT is likely to cause problems?  Something about the new fluid loosening up deposits....  I didn't let it stop me from changing it on the few cars I've owned in that category and experienced no problems.

 

I've heard that over the years with high mileage/poorly maintained cars.  It is why some recommend only doing a pan drop, and not try to do a full flush.

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45 minutes ago, MikeC5 said:

Anyone hear the old mechanic wife's tale that changing the auto trans fluid on a high mileage AT is likely to cause problems?  Something about the new fluid loosening up deposits....  I didn't let it stop me from changing it on the few cars I've owned in that category and experienced no problems.

Mike first thing done to a new old car is change every fluid assuming it needs it (understand OP has history sovhis question is a little more specific).  On ATF, trans shop I trust is good with, and encourages changing but discourages flushing they would do on a known interval at say 30,000 miles.  Instead, change once (obviously filter also) and again at around 7,500 to 10,000 down the road.  Yes, you live with mixing some of the old with the new but it seems like a good course of action, assuming no trans issues presenting themselves.  They have done a couple of sessions for our AACA region that have been informative.

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In the old days, the guideline was to change transmission fluid every three years, or 30,000 miles, whichever came first. Your best bet on newer vehicles, according to both Hogarty and LeBlanc is to see what the manufacturer recommends. Some transmissions need regular maintenance, and others are dubbed a "lifetime fill" and can go up to 150,000 miles between oil changes.

"When in doubt, service the transmission with OEM fluid and filter starting at 60k, and every 30k afterwards," 

Motor Oil

"It's most important to check your oil regularly," Hogarty says. "Low oil level is far worse than not meeting some kind of regular interval."

The intervals he suggests for car motor oil changes are 5,000 miles for synthetic blends and 10,000 miles for full synthetic. Hogarty also recommends the synthetic blend to customers, so that they can get their tires rotated with every oil change. LeBlanc sticks by an old standard, suggesting that the rule of thumb for oil change intervals is 3,000 miles for conventional oils and 5,000 miles for synthetics.

 

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13 hours ago, MikeC5 said:

Anyone hear the old mechanic wife's tale that changing the auto trans fluid on a high mileage AT is likely to cause problems?  Something about the new fluid loosening up deposits....  I didn't let it stop me from changing it on the few cars I've owned in that category and experienced no problems.

 

If that kills it, it was already dead. Everything lasts better with nice fresh good lubricant instead of old stinky broken down lubricant. Automatic transmissions are no exception. Drain everything if possible.

 

Just be sure the fluid is compatible. There are a lot more types of transmission fluid now than there used to be.

 

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2 hours ago, plymouthcranbrook said:

Well for 13 years I have been meaning to change the trans and diff fluid in my 1980 Volare. Had 8500 miles on it when I bought it and about 31,000 now. Still mean to do it, sometime. No noises or issues to this point.


Oh, c’mon there ply’ : I know that you know better than that. I mean, we don’t wait until the point where noises or issues remind us we should have changed out old lubricants with condensation in them accumulated over the course of years. This is just a suggestion. A pep talk, if you will. Because I see that you entered official old age a few months ago in December. I will be 77 in a couple of months. Disabled, and in poor health, lots of things in my life get put off. I am literally horrified to realize that every day I am falling farther behind. This is a forum dedicated to enjoyment of old cars. Lots guys here are more disabled than you or I. So in the spirit of AACA brotherhood, I suggest that you simply farm out the oil changes, and rest easy. Synthetic lubricants, please, and I sincerely hope that you and your car survive long enough to have to do another change or two. 😇

                             
                         Your aging, fading, forum friend,      -     Cadillac Carl 

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On 4/29/2021 at 9:37 AM, MikeC5 said:

Anyone hear the old mechanic wife's tale that changing the auto trans fluid on a high mileage AT is likely to cause problems?  Something about the new fluid loosening up deposits....  I didn't let it stop me from changing it on the few cars I've owned in that category and experienced no problems.

I had one that fluid was finally changed at 140k miles. I was leery of doing it. I can say it didn't shift any better, but it didn't shift any worse either.

 

A friend had a mid-80s Chevy box pickup with close to 150k. Fluid was funky but it shifted normally. He drove it into the service bay. Changed fluid and filter and the truck then wouldn't move under its own power. I think a lot depends on individual vehicle, and that one was on the verge of dying anyway.

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14 hours ago, C Carl said:


Oh, c’mon there ply’ : I know that you know better than that. I mean, we don’t wait until the point where noises or issues remind us we should have changed out old lubricants with condensation in them accumulated over the course of years. This is just a suggestion. A pep talk, if you will. Because I see that you entered official old age a few months ago in December. I will be 77 in a couple of months. Disabled, and in poor health, lots of things in my life get put off. I am literally horrified to realize that every day I am falling farther behind. This is a forum dedicated to enjoyment of old cars. Lots guys here are more disabled than you or I. So in the spirit of AACA brotherhood, I suggest that you simply farm out the oil changes, and rest easy. Synthetic lubricants, please, and I sincerely hope that you and your car survive long enough to have to do another change or two. 😇

                             
                         Your aging, fading, forum friend,      -     Cadillac Carl 

Oh I know better Carl,  but sadly inertia and old age have set in. Maybe this year. On the 2016 Traverse I bought last summer I changed everything but the air in the tires.  As said in the military”No excuse Sir”

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6 hours ago, rocketraider said:

I had one that fluid was finally changed at 140k miles. I was leery of doing it. I can say it didn't shift any better, but it didn't shift any worse either.

 

A friend had a mid-80s Chevy box pickup with close to 150k. Fluid was funky but it shifted normally. He drove it into the service bay. Changed fluid and filter and the truck then wouldn't move under its own power. I think a lot depends on individual vehicle, and that one was on the verge of dying anyway.

 

I used to have a '90 Buick Regal with the 440T-4 transmission.  Pan drop and fluid/filter at 30k and 60k miles.  Then around 75k miles, the 1-2 shift started clunking - depending on how heavy your foot was on the gas.  Dealer dropped the pan and found bits of a thrust washer in it.  They, and a couple of other transmission shops, told me to just drive the car until it dies - then install a new one.  So we drove the car another 15 years, and at least 200k miles (odometer broke - twice), with occasional fluid/filter changes.  It still had the same tranny when I sold it.  Postscript: Sadly, I found it in a Pick N Pull about a year and a half later.  Nearly broke my heart as it had been in the family since new.

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