Auto trans oil replacement?

[Guest jcc3inc]

Good Morning,

Although I have sold my 91 Reatta, it has been replaced by a low mileage 93 Riv. It has 56K miles on it and is in excellent condition in many respects. The previous owners neglected the maintenance on it, however I would like to keep it in fine condition.

Since this forum is attended by many very knowledgeable owner/advisors, what would you advise regarding trans oil change/flush/other for this car?

On a recent trip from CHI to IND I got 32.5 MPG, carefully calculated! That's the best I have ever gotten on any car!

Regards,

Jack C.

[padgett]

If fluid is pink and everything works properly, it is probably good. OTOH it never hurts to replace the fluid but think I'd just have an express place "flush and fill" rather than dropping the pan (unless it leaks) and replacing the filter.

Those later Rivs can get very good MPG on the highway. I've seen close to 40 mpg from a Series II in a LeSabre.

The "C" in most of our Reattas is not that good - I have averaged 27 on the Interstate before (Ft. Pierce to Orlando with headlights on) but only see 30 mpg on the flat below 60 mph.

Could stand a bit more leaning out I suspect but would rather run a little rich for longetivity since do not drive that much.

Edited December 21, 2011 by padgett (see edit history)

[Guest NEMO]

Drop pan,wipe clean,replace filter and new o ring . Place the gasket on the pan and start the bolts threw the bolt holes.1/2 way, NOW put a little blue locktight on all the bolt threads.Install pan to tranny and start all the bolts into trany,when all the bolts are started you can then tighten them to the required amount. Install new fluid to the required level. Drive check level of fluid,check for leaks. Leave a piece of cardboard over night, under the car to see if any leaks appear.

[sfair]

Could stand a bit more leaning out I suspect but would rather run a little rich for longetivity since do not drive that much.

Would not the computer set mixture for ALL cars at stio over which the driver/owner has no control, malfunctions excluded?

[padgett]

Drive doesn't but can control the tables used by the ECM used to manage the pulse width of the injectors. While 14.7 is the theorectical value if running on octane with unlimited burn time, modern gasolines tend to burn slower.

Meanwhile the Reatta uses a crude Zirconium O2 sensor "At a stoichiometric air-fuel ratio (14.7:1), the generated O2 sensor voltage is about 450 mV. The Engine Control Module (ECM) recognizes a rich condition above the 450 mV level, and a lean condition below it, but does not detect the extent of the richness or leanness. It is for this reason that the Zirconium O2 sensor is called a “narrow-band” O2 sensor."

This means that the ECM has to make a guess about the proper mixture for any condition other than close to stoch and uses BLM (long term) and the Fuel Integrator (short) to approximate the guess.

One problem is that the ECM calculates the advance curve as a function of rpm, load, and mixture but has no adjustment for advance, that can retard if it detects knock (OLDPA3 has a count) but not compensate with the additional advance needed for a slower burning (higher octane) gasoline. In other words, always use 87 PON at sea level.

Now one of the things that can be diddled in the PROM is the advance curve but takes a lot of care, it is an easy way to burn pistons.

BTW Most external "chips" just add a reistor to the MAT (manifold temperature) sensor in the air cleaner. To have a real effect, it needs to go inside the ECM.

[handmedownreatta]

the way people complain about these transmissions not lasting,adding a trans cooler [or larger trans cooler]at the same time may be a good idea.

[padgett]

Who complains ?

[Barney Eaton]

Padgett and I live in places that a transmission benefits from a cooler.

If you think about it.... transmission fluid goes to the radiator to be cooled, if the radiator is running at 180-200 how cool does the fluid get?

An external cooler is cheap transmission insurance.

Back to your original question. If you plan on keeping thes Riviera for the long haul, then change the fluid, and filter.

[Guest Richard D]

I am tempted to attach two thermocouples, one to the inlet and one to the outlet of the radiator tranny cooler with some kapton tape (or something like it) and see what the fluid temp is going in and coming out with a 180 degree thermostat. Anybody else done this?

[Barney Eaton]

Go ahead and let us know what you find.

I have a 2011 GMC pick-up with a transmission temp gage. Don't know where it is located but have never seen the temp higher than 171 but I don't monitor it constantly.

[NTX5467]

Trans fluid is usually good to about 270 degrees F, probably higher with the syn-blends or full-syn versions. Fluid temp can build under throttle and load, but will build much quicker when the trans is being used for braking or in "over-run" in lower gears.

A quicker way to check fluid temps, but with the vehicle stopped, is an InfraRed thermometer. I found one at Harbor Freight (online) for $19.99, which goes to about 1000 degrees F.

In the earlier days of flush machines, there were MANY variations, especially in the less expensive models (which many shops purchased!). An operator had to stand there and match the "input" and "output" flows, to keep the front pump from cavitating. Others used other means to automatically do things. BUT you still have to have good connections where they tap into the cooler lines at the radiator . . . which can be problematic in itself.

The ideal thing would be to get a quality flush done AND then drop the pan and change the filter and such. This way, you can see the residual metal from clutch pack wear and such . . . and remove it. Plus get a fresh filter in it, too!!

Dexron III-type fluid is still around, now labeled "Multi-Make" in many cases, but if you read the back of the oil bottle, it mentions the primary spec it meets is the GM DEXRON III spec. Most also meet Ford Mercon V specs, too. The new DEXRON VI is a semi-syn fluid with much longer life than the DEX III fluid.

Just some thoughts,

NTX5467

[jonlabree]

What portion of the radiator is used by the transmission cooler? Anyone???

[sfair]

Go here and ask your question. Many knowledgeable folks over there:

Transmission Forum

[padgett]

I just keep the whole engine cooler.

[Guest blue72beetle]

Padgett, I think you've said this before, but do you have a source for reprogramming the ecm, exactly what they need, and how much it costs?

And yes, I know you need to go to a 180 degree thermostat at the same time.

I figure winter would be a good time to get the chip in my vert done since it's put away until spring.

[Roadster90]

Young man on the forum several years ago (forget his name presently - had a red roadster and was a very frequent contributor to the forum) had developed a unique way to change ALL of the tranny fluid....maybe someone will remember his name ?????

Would be a positive if his procedure was incorporated into Ronnie's site....

Nic

[padgett]

Believe Ryan at GMTuners does it professionally.

[waltmail]

Drop pan,wipe clean,replace filter and new o ring . Place the gasket on the pan and start the bolts threw the bolt holes.1/2 way, NOW put a little blue locktight on all the bolt threads.Install pan to tranny and start all the bolts into trany,when all the bolts are started you can then tighten them to the required amount. Install new fluid to the required level. Drive check level of fluid,check for leaks. Leave a piece of cardboard over night, under the car to see if any leaks appear.

That process only replaces the dormant oil in the pan and is an incomplete job. The tranny holds about 10 qts( IIRC ) and your method only replaces 2-3 qts. I have done a complete fluid change, by disconnecting the fluid line to the radiator, and using the running engine to pump the TC and case fluid out. The trick is to start and stop the engine when the fluid ceases pumping and top it off to repeat the procedure until the fresh fluid begins to show up at the end of the cooling line. Maybe this is inexact, but it is much more complete than the 2 qt change in the pan.

[Guest NEMO]

You get more then 2 quarts when you drop the pan. More like 6 to 7 quarts,you would know that if you have done it. What about the dirty magnet, and sediment in the bottom of the pan,you have to drop the pan to clean .The filter needs to be replaced ,only removing the pan can do this. Pumping the fluid out by opening the line? then mixing old fluid with new,when do you know all the fluid has been replaced? change of color?

[waltmail]

You get more then 2 quarts when you drop the pan. More like 6 to 7 quarts,you would know that if you have done it. What about the dirty magnet, and sediment in the bottom of the pan,you have to drop the pan to clean .The filter needs to be replaced ,only removing the pan can do this. Pumping the fluid out by opening the line? then mixing old fluid with new,when do you know all the fluid has been replaced? change of color?

I never said , "do not drop the pan", so I don't know why you are acting all offended. I don't remember getting 6-7 qts out of the pan, but you may be correct. I have done it. Reread my technique and it will let you know how to determine when the process is completed. Sorry I tried to help out with a technique that has worked for me and many others.

10 Min Atomatic Transmission Fluid Flush + Replacement (Most Cars) - YouTube

BTW;

I found this in an interesting article.

As to the technique for making shifts more assertive- it has to do with fluid type and fill level. I'm seeing a lot of transmission people who say the 440T4 requires either one, or 2 1/2 QUARTS more transmission fluid than the dipstick indicates. The danger of course is that if you over-fill, the fluid can get in moving parts, froth and be ruined. I drove my car to Brattleboro and checked the fluid in the parking lot, where it indicated it was basically 'full'. I added an additional quart, checking as I went, and got it to the recommended inch or so above the 'full' line- maybe not quite as much as that. I drove home, and the transmission worked fine, and I checked again once I was home and the fluid was not foamy- and in fact my driveway might be overly tilted as the fluid read too low! On the strength of that I added the other quart, which didn't change the reading particularly. Conclusion- it's true that on the 440T4 transmission the dipstick is labeled so low that the transmission will starve of fluid in some conditions- I think I've noticed it losing grip in left turns, and at some other times.

The final discovery is about transmission fluid type. You got Dexron, Mercon, Type F, 'Trick Shift' etc. It seems that if you put Dexron in a transmission that requires Mercon or Type F, it dies because Dexron is much more slippery (both have heavy detergent additives). The reverse is not true, apparently. If you put something like Type F in my transmission, which is designed to work with Dexron, the fluid works normally _except_ that with less slippage agents, it locks up more tightly and shifts become more noticable and direct.

http://www.a-body.net/forums/archive/index.php/t-741.html

Edited December 22, 2011 by waltmail (see edit history)

[Rawja]

NEMO: I've deleted your last two posts.

I'd say Walt provided an end point for his described procedure:

repeat the procedure until the fresh fluid begins to show up at the end of the cooling line.

Probably a combination of the two techniques would provide the maximum fluid change, pumping 'till clean fluid comes out and then dropping the pan and replacing the filter. Probably would use a lot of transmission fluid though..

[padgett]

So real answer is to do both: drop and clean the pan and replace the filter, then use the pump method to flush the rest (which I think is mainly in the torque converter).

[Guest NEMO]

The question is when do you know when fresh fluid is coming out? How is this determined? As to droping the pan, where is this stated in the post?

[Rawja]

Padgett: Wouldn't you do the pumping out of the old fluid first? Seems like otherwise you'd be pulling dirty fluid through the new filter, no?

[padgett]

Color should be lighter.

BTW the original question was "what would you advise regarding trans oil change/flush/other for this car?"

Raja summated "Probably a combination of the two techniques would provide the maximum fluid change, pumping 'till clean fluid comes out and then dropping the pan and replacing the filter. Probably would use a lot of transmission fluid though.. "

My thought was to change the filter/clean the pan first, refill then disconnect the return line and pump out the TC to use the least new fluid.

and to respond to the post that came while I was typing: doing the pan then filter & refill changes the body and sump. Opening the drain line keeps the dirty oil in the TC from going back into the sump.

That said with a 56k car I probably would not bother unless the fluid was dark or smelled burnt and then would drop the pan to see if anything falls out, not just exchange.

Edited December 22, 2011 by padgett (see edit history)

[Guest NEMO]

I watched the video ,the fluid is BLACK when it is draining,where is the drain plug on the reatta? there is none,unless it has been added. In the video it states NEVER let the hose run dry when pumping the fluid out it could damage the tranny. I will stick to the the service manual recomendations on this on.

[Guest NEMO]

Where is the DRAIN LINE ? or is that the line from the radiator returning fluid to the trany?

[sfair]

.

That said with a 56k car I probably would not bother unless the fluid was dark or smelled burnt and then would drop the pan to see if anything falls out, not just exchange.

And there is the question....50% of qualified transmission techs say change the fluid, the other 50% say leave it alone. Both have various reasons for doing so that all seem to make sense. It is a pickle!!!

[padgett]

How does Jiffy Lube/Mobil Express do it ?

As I said, under 100,000, I probably would not bother unless there was a reason. Yer pays yer money and yer takes yer chancet.

[waltmail]

It is just not that difficult. I have done it on the Reatta. I have done it on Ford AODs, C4s,C6s. I have done it on GM TH350 & 400. There are 2 lines coming to the Transmission case. One is pump out and one is return. All transmissions have this in common. One goes into the radiator and the other comes out of the radiator. I would want to grab the one coming out since you would also be changing the oil in the cooler section of the radiator but you would need a fitting to tap into this bung. So if this is too difficult, just disconnect the pump out line ( much easier ). The clean fluid will be quite obvious. I apologize for creating such a point of contention as that was not my intention. Hopefully some will find this useful. I am not trying to win a competition.

[padgett]

Imagine that a fitting and about 6" of line would be easy to acquire at a recycling center. Suspect many cars use the same fitting.

[Guest NEMO]

I would not pump the tranny dry then add more fluid .Running your car untill the fluid gets to the condiction where it turns color is not a good way to maintain your tranny. Removing the pan and cleaning all that you can get at, filter, magnet, and inner pan is the way to go. You can remove the lines and blow out the radiator cooling part too with compressed air low pressure,but how far do you need to go. If the car has never been properly maintained you would spot this when you look at it when buying it. Unless this car has it only service before selling it. I keep a running log of Everything that is done to All my cars,trucks, motorcycles,snowmobile,and the lawnmower,and I keep a record of repairs I do to my home as well. It lets you go back to when the last time something has been serviced.

[jonlabree]

Thanks for all of the great info.

What portion of the radiator is used by the transmission cooler? Anyone???

[padgett]

Is a crossflow so the tanks are on the sides. The trans coils are in the passenger (cooler) side. Coolant temp sensor is by the block outlet so the coolant on the passenger side will be considerably cooler than the dash gauge registers. Also a liquid-liquid heat transfer is much more efficient than air-liquid.

Edited December 23, 2011 by padgett (see edit history)

[jonlabree]

THANK You Padgett.......

[Barney Eaton]

I watched the video and will wait for the book........ below are my comments.

No the Reatta does not have a drain plug, most GM cars do not have transmission drain plugs, however trucks do.

In the video they drained the pan because they had a plug, in a Reatta you need to get the fluid out some way. You can (1) drop the pan which is messy when full of fluid (2) attach the hose to the cooler line, start the engine and pump out roughly 3 quarts and turn off the engine, then drop the pan. (3) with a small hose, syphen out the pan thru the filler tube.

If you do not know the condition of the filter and/or the car has over 60k, I would pull the pan and replace the filter.

With or without a new filter, now fill the transmission with new (correct) fluid. In this exercise, it will not hurt to put an extra quart in as you are going to take it out immediately.

(remember how many quarts you added)

Now put the cooler line extension hose into a container, ideally something around 5 quarts.

Start the engine and watch the container fill..... turn off the engine when the container get to roughly 3 1/2 quarts.

Refill the transmission, empty the collection container, and start the engine (repeat above)

Reatta specs call for 11 quarts to fill the transmission/torque converter, the above will take 3-4 times to flush all the old fluid and get clear new fluid coming out the hose.

Finish by topping off the transmission, reattach the cooler line and check for leaks.

Below is a transmission temperature chart that show life expectance at different tempatures, I found this on the internet and the original source is not given. If the chart were gospel, then you need to keep the temp below 200 or you are going to replace them in under 50K.

I suspect that might be true if the temp were at a constant 200 but they don't run that hot in the winter etc.

[padgett]

I *suspect* (would need to run some tests) that the radiator cools the coolant about 15 degrees minimum but is going to be related to the incoming air temperature. I have no problem holding 180-185F on hot days (may have an excursion to 190 for a minute or two when stopped at a light but comes right down when HI fan turns on.

This means the coolant over the trans coils is probably in the 165-170F range when warmed up.

OTOH a stock car may have excursions to 210 under normal conditions and it would not surprise me if the coolant is sometimes hotter than the trans fluid. In this case, an external cooler is a good idea.

Might also be a good idea for extreme cases of very hot, dry air (In Florida while people always complain about the heat, it rarely - didn't last year - gets above the mid-90s.) 95F/95% is bad for people and some woods but the dense air is good for an engine and cooling same.

Is also Green from the standpoint that less heat is being dumped into the atmosphere but that is stretching things a bit. Also some people run a higher weight oil (e.g. 10W-40) to compensate for a worn engine. I have not had to do that & just run 10W-30 in everything except the Judge (straight 30W Valvoline Racing)

The bottom line is that I have found no downside to running the engine (and everything related) about 10% cooler than the design point. It does mean that maintenance must be kept at a high level but I upgrade to Delco ignitions and Rapidfire platinum plugs as a matter of course. It works for me.

[Ronnie]

There is enough good info in this thread to do a tutorial on flushing the transmission. I'm putting it on my to-do list.

I find lots of faults with the way the flush is done in the video. The filter was not replaced, debris in the bottom of the pan was not cleaned out, etc. I'm not sure the guy in the video knew all that much about transmissions either. He reminds me of all the actors you see on DIY shows on TV with the British accent. They don't know which end of the hammer you hit a nail with but they try tell you how to do it.

I'm not a fan of flushing on a regular basis. I don't think it is needed. I only would do a flush on a high mileage car that I don't know the history of the maintenance that has been done. I wouldn't do a flush without dropping the pan and changing the fluid and filter first.

I think If the pan is dropped and the filter replaced at regular intervals, as described in the manual, it will keep the fluid clean enough. If the factory engineers were smart enough to build the transmission, they were smart enough to know when to change the fluid. If they had thought that the fluid needed to be flushed along with dropping the pan and replacing the filter they would have wrote that into the routine maintenance instructions.

The life of the transmission has more to do with how the vehicle is driven and doing scheduled maintenance than with getting every last drop of fluid out when you change it.

[padgett]

Just one thought: the 90 Reatta had a 3 year 50,000 mile limited warrenty. Under normal driving, transmission service (including filter) was not until 100,000 miles.

Under heavy duty e.g. city driving over 90F or police/taxi, exactly where my extra cooling comes into play, transmission service is at 15,000 miles but is "normal maintenance" and not covered by a warrenty.

So the drain is not expected to be needed for any normal service or inside warrenty. If you figure the mod to the pan and the drain plug is a quarter, then for two million transmissions some bean counter just saved the General a half million bucks.

Of course I have never seen a stock automatic transmission or gas tank with a drain plug so may just be tradition.

[Ronnie]

I've always followed the factory recommendations for changing the fluid. For the last 20 years I have always removed 2 quarts of transmission fluid and replaced it with Klotz (#KL-930) - Racing TechniPlate 10W/30 oil. It is a red oil that looks like transmission fluid. It was recommended to me by a mechanic I once worked for who was a wizard on automatic transmissions. I was having a problem with a vibration when the torque converter would lock up and it cured it. When I first got my Fiero Formula the converter would sometimes stay locked when I came to a stop. (Talking about a scary situation at a stop light!!!) After running the Klotz for a while it stopped the converter from sticking and seemed to make the whole transmission shift smoother. Good stuff but use at your own risk. Your results might be different.

Torque Converter Shuddering/Sticking Fix*-*ReattaOwner.com

I've only had one transmission fail prematurely. It was in a F**d Taurus at ~72,000 miles. An aluminum clutch hub broke. Changing fluid more often would not have made a difference. Replacing the aluminum hub with a steel one did.

I sold an S-10 pickup a couple of years ago that had 230,000 on the clock. Fluid was changed according to the maintenance schedule. Fluid always looked red and clean. It had Klotz in it. If you see black fluid as described in the video it is because the transmission has been overheated due to towing or abuse OR the clutches in the transmission are slipping and excessive friction, due to slow lockup, is burning the fluid. The fluid should not turn dark due to contamination from burned hydrocarbons as it does in motor oil.