I have an '89 Buick Skylark 2.5l with 200K on it. I'm about to replace the radiator since there'* a leak in it and it may be the original radiator. My fluid looks pink and when I looked in the shop manual, it said to replace oil cooler and if that doesn't work, to service the transaxle. It said to replace the fluid at 100k under normal driving conditions. I have only 46K on the oil but it is ten years old. Besides heat, will time break down oil? Right now, when the car is cold and I take off, unless I gun it, it takes awhile to shift out of first into second. I got the car for free from a dealership back in 2001 and they said the engine had been rebuilt but I don't know about the transaxle and I don't take dealerships for their word. Thanks.

On my Buick Martin I use Dexron VI (6) and change it with new filter every 40k-50k miles aprox.
I always believe fluid is cheaper than transmission rebuilding, and keeping fluid clean is a good preventative maintenance plan.
Every time you drop the transmission pan you are able to look for particulate matter and your transmission will definitely benefit from the latest Dex6 synthetic fluid.
Dropping the pan does not remove all the transmission fluid, lots still remains in torque converter etc.
If you really wanted to replace all the fluid, finding a shop or dealer with a transmission fluid exchange machine would be best for longevity.
Does your skylark have a engine oil cooler ? I am not familiar...It may also have a transmission fluid cooler.
Look and trace the lines...Some may have transmission cooling though tank in rad.
Heat Time and overall driving with fine clutch plate normal wear material, is enough to change the transmission fluid at 40-50k intervals in my mind. Hope this helps.

Thanks for the second opinion. Yeah, I feel with the amount of miles it has on it, it may be good to drop the pan and change the fluid. It was sitting for three years before I replaced the fuel pump and could have had condensation develop...who knows? I just ordered a radiator for it from Rock Auto since the radiator leaks coolant anyways. The passages may be blocked from the Bars Leak I have put in the system. Yes, the tranny'* lines run into a tank on the side of the radiator which is sealed off from it.

Problem with constant transmission flush'* is, every time you do it, you flush out clutch material. With older worn out transmissions, you need this clutch material to stay in with the fluid. So I recommend 1 time change, NOT flush over to Dex 6.

Mike, I have heard horror stories of transmission flushes.....not sure what happened though.....maybe these were the so-called reverse flush machines?

The machine we used, was kind of like a fluid exchange machine......the car pumped the fluid out into the machine, and the machine pumped fluid into the pan......

I am not sure what you mean about flushing out clutch material.......the clutch material, if any, is in the bottom of the pan.......it'* not going to get by the filter anyway......the machine is not going to force more clutch material out.....the machine does not have anything to do with circulating the fluid, the tranny'* own pump does, so there is no excessive pressure here....

I think the main problem with flushes is, some garages just flush and don't drop the pan and replace the filter(they add a chemical to clean the tranny, and this could possibly plug or partially plug the filter)......another problem is, some people expect miracles......if your transmission fluid is dark/burnt, most techs will try and sell a flush......but by now, the damage is done.....in cases like this, a flush may accelerate a potential problem......

Flushes are preventative maintenance, not a cure.....

GM has their 100K schedule....with Dextron III, we recommended 3yr/36K service......with Dextron VI, we recommended 5yr/60K.....

How often do you guys recommend fluid changes?

How do you guys feel about flushes?

Flushes without a filter replacement? More expensive, because more fluid is used...

use mobil 1 in a 1991 ford Taurus transmissions failed at 70k all the time bad design on some of the system and every one knew it ours went 158k
before it went out double the life of a know problem transmission
2001 buick regal transmission went 278K before input shaft shared
mobil 1 in it from new clutches still looked new bearings all great
now this it with 30k changes the stuff is like gold

"Flushes without a filter replacement? More expensive, because more fluid is used..."


Sorry, meant "with", not without....

Sorry, I should have elaborated more. Doing a pan drop removes clutch material that is usually suspended in the oil that the filter doesn't trap. I've read in many circles that if the fluid is still pink/red and doesn't smell burnt, leave it in their.(old trans) And I've even seen in some instances with a high mileage trans that if you do drop the oil it becomes even worse. Slipping.

Flushing? Yea, I'm not fond of those either. All they do is suck out the old and put "new" in. But is it really new? Are shops saving a buck by filtering YOUR old oil and putting it in someone else'*?

And as the old saying goes, no such thing as a quick fix in a bottle.

I haven't ever seen any place that filters old oil and reuse it. It would be illegal unless they said it was recycled fluid that was being used.

How many shops do everything "legal"? Just sayin.