Who Changes Their Own Tranny Fluid?

[Outbacker]

Is it a simple job to do on the GMT900? I changed oil on a tranny a long time ago, did the gasket and new filter thing, and it seemed to go alright. I plan to switch over to synthetic oil, but to do this I am thinking that a flush may be required to get all the oil stuff out. What about the torque converter? At the end of the day it is better to get a tranny shop to do it?

 

Thanks.

[GMAnimal]

Draining the pan only gets almost half of the fluid out. Not sure how the best way is to changeover to synthetic.

[iminaquagmire]

It already is synthetic. GM switched for the GMT-900 platform. Its DEXRON VI now.

[crepitus]

i think it is semi synthetic according to another post going on now.

 

http://www.gm-trucks.com/forums/index.php?showtopic=86050

[longhorn_giant]

as for ease of change, I haven't done it yet but I was crawling around under the truck and noticed a couple things:

 

There's a lip on there that you can use to help hold one side of the pan while working with the other side. Makes changing it by yourself much easier.

It looks like you'll have to remove a bracket (throttle line?) to get the pan to drop completely off. There's a couple torx head bolts on the top of it that you have to feel your way around to find. The same bracket was there on my '02 when I changed the tranny fluid in that. I found out the dumb way that they were torx heads, stripped them, and resorted to bending the bracket out of the way to drop the pan, then bent it back when I was done.

 

Other than that it's pretty straight forward to drop and change.

 

Hope that helps some.

[Rat4go]

Word is that DEX 6 is pretty good stuff....why change unless you have lotsa hard miles on the truck already??

 

What I've done is the past was:

 

1. Disconnect a cooler line at the radiator (bottom one) and put a hose on the end of that line and ran it to my drain pan.

 

2. Start the truck and run 'til the oil stops 'streaming' from the line (this means the pan is mostly empty). Should only be a minute or two tops to do this.

 

3. Remove pan (easier now that there's not 6 qts of fluid it it)

 

4. Replace filter

 

5. Replace pan

 

6. Add 6 qts of fluid

 

7. Repeat the 'run til the oil stops streaming' thing (this takes the new oil from the pan and uses it to push out most of the 'old' oil from the converter)

 

8. Reconnect cooler line

 

9. Add 3 qts of fluid

 

10. Start truck, check fluid level to the 'cold' marking on the stick and add to get near the cold line.

 

11. Warm trans up to proper temp and check fluid level

'hot' and add as required (should be about 1-2 quarts low as I think a dry trans takes about 11 qts)

 

This isn't a 'perfect' converter flush as old and new oil will mix, but you should get most of the 'old' stuff out. This also won't flush oil out of the cooler line that goes from the radiator to the aux cooler (if you have one) and back to the trans.

[C & A s Dad]

I agree somewhat with the previous post on flushing it at home.

Mine has a drain plug so I drained, changed filter, filled with fluid and then disconnected the line going to the cooler in the grille.

 

I recommend pumping out one qt at a time. Pump out a qt, add a new qt, pump out a qt, add a new qt until the fluid you are pumping out is as clear as what you are adding. It will take about 15 or 16 qts total to do this job. I would not want to let the truck pump out all the fluid in the pan until it was sucking air. I would rather do a qt at a time and BTW, you will need a 2nd person in the truck to start it and kill it as you are pumping the fluid out.

 

Amsoil has some really good detailed instructions on their website.

 

To Outbacker, I would tell you the entire job is really easy on an 800 series truck and I cannot imagine much as changed on your 900. Just know that when you finish the job, you should have trans fluid in both armpits and behind at least one ear. If not, you have not done the job properly.

[c4cruiser]

In my 08 owner's manual, a tranny service is shown at 100K miles in "normal service" Unless you regularly beat on thetranny or haul a big trailer or heavy loads, the 100K service interval should be OK. The fluid listed in the manual is Dexron-VI

 

The best way to have all of the old fluid flushed out is to have a shop do it using a flushing machine made for that purpose. All of the old fluid will be replaced with new and there won't be any worry about mixing old fluid with new. A filter change is done as part of that process and one good thing is that you don't have to deal with the mess followed by hauling off 4 gallons of old ATF.

 

Local stores have Dexron-VI for around $6 per quart. The Valvoline stuff is shown as a full-synthetic. If a complete flush and fill takes 16 quarts, that's a cool hundred bucks before the filter.

[DofD]

I would take it to a shop where they have the equipment to flush the fluid out and then have them fill it with the fluid I wanted.

[iminaquagmire]

Whoops. Dexron VI is semi-synthetic. Valvolene's Dexron VI is fully synthetic.

[chuck16]

Outbacker,

WestShore Transmission off of Dunford

http://www.westshoretrans.com/map_hrs.asp

Look for the Coupon on their site too

 

I had my truck serviced 4 years ago there and the next time it's up for service; it's going back there again.

 

Automatic Trans jobs are just one of those jobs I'd just rather not do!

 

-Evan

[C & A s Dad]

The flush machine method is no magic. Many of these machines use the internal pump inside your trans to push out the old fluid just as what I described in an earlier post. The difference is the old fluid is contained in large reservoir instead of you catching it in a jug. Some use a reverese flush method and these machines do have their own pump. I personally do not like the reverse flow method.

 

Someone also mentioned the filter being changed along with the flush. Do not assume your shop is doing this. Many shops have bought into the falsehood that a filter can be flushed clean and they simply do not change the filter. A paper media filter cannot be flushed clean and most all trans filters use a paper media.

[Outbacker]

It already is synthetic. GM switched for the GMT-900 platform. Its DEXRON VI now.

 

I asked my service department about the type of tranny oil I have, and he told me that it is regular dino tranny oil.

[C & A s Dad]

Bob, if you are talking about the fluid in your 08, your Service Manager is mistaken. GM began using Dex VI sometime in 06. All 07s and 08s use it as well.

 

I thought it was a full syn but others have posted that it is a semi syn.

 

I have found that many Service Consultants are far from being "car guys" and do not keep up with changes. I can remember that many of them continued recommending 20W 50 motor oil long after all mfgs had moved to 10W 30.

[Outbacker]

That is very interesting, and I will definetly follow up on this by calling different dealerships asking this very question. That was the main reason I wanted to change it out as I was told it was regular oil. Thank you very much.