Transmission Service Questions

[jay webb]

nothing saying you cant do it at 25k ,. its just not needed. 

 

also a pan drop and filter change is only going to get about 6qts of fluid. 

 

a trans fluid exchange will get bout 90% of it. 

 

typically we recommend trans and transfer case services at the dealer ship every 45k (auto tech for gmc dealer) 

 

and considering you have dexron vi in the system already and you arent exchanging all of the fluid i would recommend just using the same oem fluid. 

 

this is what i recommend,

oil change tire rotation every 5k

cabin filter every 10k 

air filter every 15-20k

induction services every 15k 

trans/transfer fluid every 45k or 30k if you tow alot/heavy duty /harsh conditions. ( that being said this order, fluid exchange (flush) 1st time, 2nd time pan drop/filter , 3rd time fluid exchange. ) 

brake fluid every 30-45k 

front and rear diff fluid ever 50k , 30k if you tow alot or heavyduty/harsh conditions 

[thatryan]

15 minutes ago, jay webb said:

nothing saying you cant do it at 25k ,. its just not needed. 

 

also a pan drop and filter change is only going to get about 6qts of fluid. 

 

a trans fluid exchange will get bout 90% of it. 

 

typically we recommend trans and transfer case services at the dealer ship every 45k (auto tech for gmc dealer) 

 

and considering you have dexron vi in the system already and you arent exchanging all of the fluid i would recommend just using the same oem fluid. 

 

this is what i recommend,

oil change tire rotation every 5k

cabin filter every 10k 

air filter every 15-20k

induction services every 15k 

trans/transfer fluid every 45k or 30k if you tow alot/heavy duty /harsh conditions. ( that being said this order, fluid exchange (flush) 1st time, 2nd time pan drop/filter , 3rd time fluid exchange. ) 

brake fluid every 30-45k 

front and rear diff fluid ever 50k , 30k if you tow alot or heavyduty/harsh conditions 

Thank you!

 

i read in several places that GM recommends NOT flushing this trans, is that false?

 

never thought of induction service on this, what’s involved there?

 

brake fluid... like flush the system?

[jay webb]

44 minutes ago, thatryan said:

Thank you!

 

i read in several places that GM recommends NOT flushing this trans, is that false?

 

never thought of induction service on this, what’s involved there?

 

brake fluid... like flush the system?

ok the way we do a trans "flush" aka fluid exchange in the shop is we hook a machine up via the trans cooler lines in series. with the truck at temp and running the trans pump pushes the old fluid out the line into the machine and sucks the new fluid from the machine into the trans. it uses the trans pump own pressure. it dont hurt the trans at all. 

 

there is a lot of mis-information  about what a flush is/isnt. 

 

a brake fluid exchange/flush at the shop, we suck out all the fluid from the reservoir, fill with new fluid. then we use a pressurized machine that we fill with clean fluid and attach to the reservoir with an cap attachment. then we go to each bleeder and crack and bleed the system 1 by 1. starting at right rear, left rear, right front and left front. then top off as needed. this exchanges all the fluid in the system. brake fluid breaks down over time and becomes contaminated. there is test strips you can buy to test your fluid. or i have seen a digital fluid tester that looks like a pocket/pen flash light. 

 

oh forgot recommend coolant every 5 yrs. typically we recommend this bout every 60k in the shop. i know dex cool says 120k or something like that. 

 

an induction service is a 3 part service. 1st is cleaning the throttle body , it gets dirty and can cause issues. throttle body cleaner and a rag is all you need. 

the other part is 2 part service, it is 1 can of fuel additive and 2 cans of a cleaner. we put the cleaner in to a contained/sealed canister and use shop air to the canister and with the vehicle at temp, install the spray/mister end into the induction tube at the throttle body. let the vehicle idol while the canister pressurizes the chemicals into a fine spray/mist it is sucked into the engine/intake cleaning deposits. once all the chemical is ran through . unhook all from vehicle. put vehicle back together. then drive it hard. heavy acceleration/load to push/burn all the deposits out of the engine. it will run rough, might misfire and blow white smoke kinda hard for a bit while driving it right after service. after it blows all the shit out it will return back to normal.   

[thatryan]

Thank you for the explanations!

[jay webb]

6 minutes ago, thatryan said:

Thank you for the explanations!

no problem. im kinda sick and tired of the reputation and mindset people have about the dealerships. are there bad ones? yea, are there crooked techs? yes! 

 

do mistakes happen? of course we are all human. but for the most part no one is trying to rip you off. 

i tend to think alot of this comes from people not being informed about the service/repair side of owning a vehicle. and the fear that comes with not knowing. 

 

so i try to offer advice with nothing held back. i own a 2018 gmc sierra myself. i have been a tech for gmc for over 6 yrs now. 

[Grumpy Bear]

 

Rinse and Repeat.

[thatryan]

I hear ya on the bad reputation. I was a technician for Toyota for several years until 2004 had to quit for medical reasons. So I’m capable and familiar and still

have my tools. Just been out of game so long I like to confirm proper procedures. Especially as I want this to be the last vehicle I buy  

[kennerz]

Anyone have the info on the recommended new Mobil 1 trans fluid they are saying to flush/replace the old fluid with?

[Grumpy Bear]

You change fluid for one of three reasons. 1.) It's been overheated. 2.) It's been contaminated. 3.) It's been depleted. # 3 would require a UOA to ascertain. # 2 is unlikely chemically unless your in tank cooler is leaking. Clutch lining and break in debris are also contaminates and a real good reason to do the first change earlier than the factory manual number of 45K. 

 

#1 is the reason I tell GM thanks but no thanks to all, interval, method and lubricant choice. This six speed has much factory interference going against it. A.) Factory fill is a Group III Mobil/Exxon product. Has only a tiny bit more heat tolerance than a Group I or II. B.) Has a 192 F thermal bypass valve (aka thermostat) Not unusual for a stock trans to run 215-225 F unloaded on a hot day. MUCH hotter towing or hauling. Hill country can get it to trip the 260 F warning. C.) The factory trans tune had the torque converter slipping much of the time to "eliminate harshness". (AKA burn down the house). This trifecta is high enough to not just cook the fluid, mine was quite done by 50K, my first service, but even IF the fluid could take it the seals and the clutch lining bonding method will not over time. A time you will not deem long enough to be satisfied with. 

 

The obvious solutions are as you intuit, change often. Use a fluid with greater heat resistance. Keep the fluid between 104 F and 180F. 104F is the lowest temp on the trans map for normal functionality and 180 F is the upper limit by serious transmission builders that have a vested interest in keeping your box alive and their reputation in tact. GM is the only IDIOT on the planet that deems over 180 F as 'normal' and 'acceptable' for 'reasonable service'. GM and I disagree on the term "reasonable". Often you can hit that window with a simple thermal valve bypass or delete. Heavy towing may require additional coolers, fans and switching. 

 

Your DIC should have a trans temp display, You can keep you fluid, even bad fluid alive by even more frequent changes but that will not help the seals and clutches. 

 

You asked for opinions. There's mine...for the hundredth time. Use it, don't use it. It isn't my truck. Beer thirty. 

[thatryan]

Thanks @Grumpy Bear I appreciate your input!

is the AC Delco a bad fluid to put back in, or is it better than the factory stuff?

 

my trans temp is usually 184-194 When I look. 
 

Would you do just pan drop drain and fills?

 

Thanks!

[Grumpy Bear]

The Delco fluid is the same as the factory fill. A Group III. Fine IF you change it often enough. I only know of two fluids that are POA/Ester blends that a mortal can get his hands on. Red Line and AMSOIL. Both are compatible with the factory fills. Both are good for more heat but......

 

Most to the transmission wear happens quite early and while factory filter may not be 'all that and a can of beans', it is what you have to work with. Dropping the pan is the only way that will get changed.

 

184F to 194F is low enough to keep the seals and clutches alive. It is right at the top limit of the Group III fluid however for fluid service life. You decide.

 

PLM alloy pans with a drain plug are available in either 6 or 8 quart capacity for your truck. It will pay for itself in one or two changes.

 

I did the first drop and fill at 50K. 6 Quarts of Red Line D6. On the second I swapped for an 8 quart pan with a drain at 70K. Did a second 8 quart at 80K and a fourth a 100K. That gets me to 95.5% POA/Ester and 4.5% Group III. I'll now do 50K drops and filters every 100K.

 

Time will tell if I'm fooling myself. Just saw a fella that did 35K services have his drop dead at 125K. Converter. Of course I have no idea what fluid, what method and more to the point what SERVICE. Hit with a big enough hammer and I can break one the day it leaves the factory.    

[Jh8473]

**** Amsoil, ACdelco Dexron 6. Dont waste your time with the filter, it wont be dirty.

[Jh8473]

I wouldn't run Amsoil in my lawnmower.

[Grumpy Bear]

3 hours ago, Jh8473 said:

I wouldn't run Amsoil in my lawnmower.

Good for you. Bad for your mower. 

[diyer2]

3 hours ago, Jh8473 said:

I wouldn't run Amsoil in my lawnmower.

You must have fallen off the turnip truck and suffered a concussion.

Great oil IMO but I won't pay for it.