auto trans fluid: flush, drop pan, or skip?
Posted 06 June 2011 - 10:13 AM
I have also had several mechanics say that it is best just to run it like it is since new fluid can cause problems. Really need some sound advice!
Posted 06 June 2011 - 01:09 PM
Posted 06 June 2011 - 01:36 PM
Well the car manual says every 100000 miles. But I would pull the pan and change the filter and maybe even the tail seal of the tranny.
John, you sure know a lot more about this than I do, and I just don't see why new fluid could cause the serious problems some mechanics warn about. I have done this before on a Corvette and had enough problems to swear I would not do it gain, but time diminishes old problems. Do you use adhesive sealer to hold the gasket to the pan while installing?
Posted 06 June 2011 - 01:40 PM
Edited by cwi inspector, 06 June 2011 - 01:42 PM.
Posted 06 June 2011 - 02:11 PM
I've heard on older transmissions like yours that putting new fluid in it with all the fresh additives actually can do more harm. I don't know if this is true or not. But from personal experience last summer I dropped the pan on my 79 TA and changed the fluid and shorlty after the transmission went out. I took a gamble on the transmission when I put the car back together wether it was any good or not. It got me throught the summer. when I took it to have rebuilt the shop said it was just wore out. So I'm not sure if changing the fluid had anything to do with it or not. Then I had a 99 dodge Ram and had the transmission flushed and shortly after it went out. So I suppose its a gamble on what you do. Sorry if I confused you more.
Bill, I am old and confuse easily. I have had the flush done on a Camaro with no problems, and did the pan and filter on a '74 Corvette, with no transmission problems. But in checking locally at two shops today to get a price on the pan & filter job ($150) they both said they were aware of problems that could result, and would not be responsible for those problems. I want to help that transmission, just as an oil change helps the engine, and sure don't want to create a problem.
The manual says to change at 50K and at 100K for normal service. I think mine was used in a normal manner, but I doubt if it was changed at any time, meaning the addition of new fluid could be a significant change. Anyone else have an idea? Please let me hear from you.
Posted 06 June 2011 - 04:39 PM
Posted 06 June 2011 - 05:11 PM
Posted 06 June 2011 - 05:44 PM
Posted 18 June 2011 - 12:20 PM
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Posted 19 June 2011 - 09:11 AM
I vote for a complete flush and filter change. Have it filled with a synthetic Dexron 6 fluid like the one by Valvoline. Its amazing how much better the trans works a week or two later. Old fluid is no good, even if it doesn't look or smell burned. Old fluid breaks down, the long chain molecules become short as they break up, and the lubricating ability drops off.
I didn't do all that you suggested, but I did drop the pan, replaced the filter, and added 4 qts. of Dexron III. The fluid now looks like new, even though a lot was not replaced. The filter was dirty, as was the magnet. I did not see any GM markings on the filter, which leads me to believe that this may have been done before. I just feel better seeing it so clean looking. Also pumped out the rear differential and put in the syn 75-90. which is clear, not like the black junk I pumped out.. Next job will be the brakes, which are working fine right now.
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