2011 Silverado Transmission Service

Have a Chevy 11 silverado 5.3L 6 spd transmission. Owners manual says to service transmission oil and filter at 80K miles. Exhaust system needs to be loosened to accomplish. My independent shop guy strongly advises against any service unless oil is dark. Oil is not dark, sees limited light towing <3k#.

Any sage advice?

Dealer wants to do a flush?!.

I am old enough this is my last truck if I take care of it.

If you do the service and the transmission has problems, you'll blame it on the service.

If you don't do the service and the transmission has problems, you'll blame it on not doing the service.

If you do the service and the transmission lasts, you'll claim the service was worth every penny.

If you don't do the service and the transmission lasts, you'll claim the service was a scam and totally unnecessary.

I've been down two of the roads. Didn't do the service and the transmission held up just fine. Did the service and the transmission held up just fine.

A flush is the correct way to do it. It gets all of the old fluid out and replaces it with all new. A dump and fill only gets about half the fluid.

Waiting until it gets dark is too late.

What you are after is the filter, which means dropping the pan.

If it were mine, I would drop the pan, replace the filter, top it with new fluid.

Flushing clean fluid is pointless.

I have been wondering the same question about my 97 S Blazer for about ten years now. Went as far as buying the new pan gasket and filter but never did change anything. Far as I know its the original oil in there and working just fine at 177,000 km so I'm probably going to just drive it. My nephew has a similar Blazer with 300,000 km on it and I believe its original oil and transmission too.

I did the service on my mothers 2012 suburban same trans. Used GM filter and gasket it's a must the after market ones leak. Rolled over 122,000 miles and torque converter went caught it quick so not a big problem $800.

I agree with Barnyard, why just do the filter then top off 5 to 7 quarts when flushing
gets all 16 to 18 quarts!

(quoted from post at 14:54:10 11/16/20) Have a Chevy 11 silverado 5.3L 6 spd transmission. Owners manual says to service transmission oil and filter at 80K miles. Exhaust system needs to be loosened to accomplish. My independent shop guy strongly advises against any service unless oil is dark. Oil is not dark, sees limited light towing &lt;3k#.

Any sage advice?

Dealer wants to do a flush?!.

I am old enough this is my last truck if I take care of it.

Click to expand...

'm a firm believer in doing fluid and filter changes at recommended intervals. The idea of waiting until the fluid is burnt sounds like a terrible plan. There is a lot of information on the internet about doing a flush. You should read up on it.

I have a problem with this so-called "flushing" of transmissions.

First thing: There are quite a few DIFFERENT transmission fluids in use these days. Each has its own
applications. There are fluids for the CVT transmissions. GM uses Dexron 6, Ford uses Mercon 5. Chrysler uses ATF
+4. They are neither compatible nor equivalent with each other. What fluid was last used in this flushing
machine?

Second thing: If you have ever seen the inside of an automatic transmission, you would see that there is NO WAY
to completely flush out a transmission without using up a 55-gallon drum of fluid. How much fluid can a shop
afford to waste to flush a transmission?

Third thing: Flushing has no value if the filter is not changed. This basically cancels any benefit that may have
been realized by flushing.

Fourth thing: There is only ONE WAY to PROPERLY flush a transmission - take it apart, clean it, and replace with
new fluid.

In my opinion as a retired transmission mechanic for 30 years, flushing is just a scam. It is a moneymaker for
shops.

Ask yourself: How much of the original fluid is still mixed in with the replacement fluid? How much of the last
job's potentially incompatible fluid has been introduced into your transmission? Do you want to trust your multi-
thousand dollar transmission to a BG gadget machine?

One other thing. Today's fluids are synthetics that are designed to last the life of the transmission.

I said my piece. You do as you wish.

I had a fancy, loaded up 97 GMC Jimmy. As soon as the warranty was up it just turned to junk, one thing after another.
The transmission went out of it when my wife backed it out of the garage, sun shell stripped in it. It wasn't the only one
, lots of them were defective. That was the most hated vehicle I've owned, think about the only that didn't break was the
sun roof and we didn't use it much.

We did drive it up Pikes Peak once and made it back alive though.

Jim .... interesting reply you post. I've always guessed that most vehicles these days go from cradle to grave with the original tranny fluid and filter in place. Would you agree with that?

This is an occasional but not frequent topic here. From reading these threads when they come up my impression is that if the first flush is done at the factory recommended number of miles you should be good. Where many car owners get into difficulty is flushing well after the recommended mileage. My personal strategy is to get it done at the first recommended interval and then just run it after that. It works for me.

Good testimony Jim, I believe that and good to know.

I would say that you are most likely correct about that. Most cars sold new never see a dealer's service department again. Most transmissions go from new to the junkyard with the same oil in them.

Pay it now, or a lot more later

Never have i heard a person say, flushing is a waste or a money maker for the Co, wow, !!! I change mine every 30,000 miles like the book says, i got 305,000 on one vechicle !

I've seen the insides of a lot of transmissions - agreed a neglected unit will take 50 gallon to flush "clean". I have dropped the pan on units that have been maintained and they look like new on the inside. Transmission fluid is extremely high quality detergentated oil and carries lots of "dirt". If you have buildups of deposits in a transmission you've neglected it.

The "filter" doesn't amount to much in most transmissions. In most transmissions its an encased screen - not a filter. If your transmission is wearing like it should the screen will never need to be changed. The clutch packs and bands should wear with such small particles that the wear material (grit) is so small it passes through the screen. If you have chunks clogging the screen you need to rebuild or replace the transmission - not the screen.

I'm big on constantly changing my fluid keeping it "fresh". On my Tahoe I replaced the pan with a deeper pan and drain plug. Every couple motor oil changes I drain the transmission fluid and refill. It gets about half the fluid with every swap. I installed a drain plug on the factory pan on my F250 and do the same with it. The E4OD transmissions need fresh fluid or they cook the oil and it gets to thin. The low pressure due to the thin oil creates even more heat and breaks the fluid down even more. The fluid is "dark" every time I change it but its still red. On my Taurus and Impala I can suck the fluid out through the dipstick hole and I change about half the fluid every 10-15K.

Interesting story on transmission oil colour. My dad bought a used 74 Monaco at auction back in 1985. Fairly high mileage but looked and ran really nice. When I checked the transmission oil it looked and smelled terrible. More like sae 90 gear oil. I don't recall if we changed it or just drove it but that old Dodge was one of the best cars ever. It was written off in a serious passenger side collision in 87 unfortunately. We took it home to decide what to do with the car as it was still quite driveable. That torqueflite transmission never gave a minute's trouble in spite of the terrible looking oil. It finally met it's demise as a demolition derby car.

I had a 2010 Silverado changed trans oil twice in 150k easy job never had to remove any exhaust , sounds like a scam

We have over 120 buses big and small , ford chevy,IH , and thomas ect... We do a bg trans flush,every two year. we have yet to change a tranny. removing the pan dosent get the fluid in the torque converter. i did my 2014 tacoma and it only had 40000 miles cheep insurance. If i had a truck with over 100000 mile and it never had a service i might think twice. thats just me.

I agree Crazy !! But people don't ready the owners manual, i bet a lot are still wrapped in the plastic !!

This discussion can go on forever, but here is my informed observation.

I am an experienced transmission rebuilder. I have rebuilt very many automatic transmissions from the domestic manufacturers as well as a few foreign ones. Every make of transmission has its own quirks and peculiarities. The technology has improved considerably over the years. More operating ranges, better friction materials, better fluids, the addition of electronics, and the elimination of troublesome mechanical components like governors and a host of "compensating" valves.

Transmission oil will get dark or discolor for only two reasons - heat or a friction element is burning up. Either one usually indicates that the transmission is nearing failure. As other posters have said, once the oil gets dark, it is usually too late for any "mechanic in a can" remedies.

Heat is the biggest enemy of automatic transmissions. The cooler you can keep them, the better they work and the longer they last. The biggest source of heat in a transmission is the torque converter. Clutches, bands, and gear sets do not generate much heat. But, heat does shorten the life of friction materials. Most friction materials are surprisingly fragile.

Each manufacturer has done mountains of research, development, and testing to develop their transmissions. As such, they have found certain combinations of fluid additives and friction materials that work the best for their transmissions. That is why you put the recommended fluids in transmissions. Will the wrong fluids work in transmissions? The answer is a qualified yes - up to a point. In the immediate "right now" moment, they will work fine. They might cause some shift quality issues, but in strictly hydraulic terms, fluid is fluid.

The problems arise in the long term. The shift quality issues I mentioned are slipping during shift, harsh engagement, delayed engagement, and slipping under load. Other issues could be incompatibility with bonding agents (the ones that bond the friction material to the metal) or electronic components. My main concern is the long term durability of the transmission.

I do not consider myself to be smarter than the people that designed, developed, and tested the transmission. Because I am NOT smarter than those people. Neither is BG company. Neither are the many producers of "mechanic in a can" products that promise miraculous results from using their products.

Flushing leaves the door open to mixing of fluids and contamination. It is also not as complete as it is claimed to be. Those who claim to have had good results from flushing could be just lucky. They might have had the same results without flushing. The automatics used in buses and medium duty trucks are so much heavier and robust than those used in cars and pickups that there is no real comparison.

You may believe in miracles in a can and third party technologies, but it ruffles my feathers to see it presented as being superior to time tested methods of maintaining a transmission.

For some reason, I think an auto tranny would have to be bigger than a 55 gallon drum.
In order to require 55 gallons to flow thru it to replace all the old with new.

Is atf a compressable fluid that shrinks in volume from 55 gallons to maybe 5 gallons in the tranny?

This is like septic tanks. Every time the topic comes up there are a few who insist that they should never be pumped, because they know someone who new someone who lived in a house for 90 years without ever getting theirs pumped.

How about this. When you introduce new fluid into the transmission, does it simply push the old fluid out of the
way? Or does it mix some and push some of it out of the way? How much has to mix and move out to replace MOST of
the old oil?

Think about this: If you do your thing in the toilet and then flush it, is the water that remains clean enough to
drink? How many times would you need to flush until it is clean enough to drink?

Ok, I can agree to that.
So now the question is when a shop does do a flush, how much new fluid do they push thru it before they call it done?

I bet it is maybe one quart over the gross capacity of the particular tranny and that is all.

How many go to their grave because the transmission failed?

If there is not a good or reasonable way to get all of the fluid out, then don't touch it right? Doing an oil change on engine is not going to get all the oil out either. Color of fluid is not the ultimate indicator of condition. The additives can break down, the fluid looks fine, but still needs to be replaced, this happens all the time usually with symptoms like T/C shudder, or other minor shift quality issues.

There's nothing wrong with wanting to replace the filter, but if it actually needed to be replaced, then you probably have bigger problems looming. Dropping a pan usually drains around 1/3 to maybe 1/2 of the fluid capacity. Many modern vehicles, don't have pans to drop and/or don't have serviceable filters. Many modern vehicles either require special tools, or special procedures just to fill the trans back up (no dipstick, or fill tube). I don't call it a flush machine, but the fluid exchange machines are the most effective way to renew the fluid in a trans.

FYI, 2011 silverado the exhaust crosses over right under the rear portion of the pan and its pretty tight. The exhaust doesn't need to be removed but loosened at the manifolds and lowered slightly.

Dropping the pan on this truck you will use about 6qts
Fluid exchange machine is going to use about 16qts.

I am not gonna get in the debacle I do somehow flush/exchange are drain and fill the ATF on my vehicles... Some vehicles are more prone to issues with ATF I have seen new vehicles need the fluid changed at 10K... For are again it makes me feel good knowing its the best are all I can do to extend the life of the trans : )

If you are in the loop like a few here you learn the ones that are the most problematic and recommend some type of maintenance on the ATF...

I am working on a 07 Suburban now with close to 500K on it we have kept the ATF serviced, as of now I would not attempt to fudge with the fluid...