4x4 concerns

[Chris]

About 275 is where the red lines start on my trans temp gauge

 

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[TheTrueMoron]

Why no gauge markings? That's my question. Shouldn't vehicles come with marking on the gauges that show the operator when the vehicle is pushing its limits?

[Chris]

Mine has them.

 

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[GMCustomerService]

When should a guy get his transmission fluid changed? Only about 60000 miles on my truck, done some towing and 4x4ing, but take really good care of it! Heard good and bad things about transmission oil changes.

It looks like the manual does recommend that automatic transmission fluid and filter be changed at 100,000 miles for regular service as mentioned. You can view more information on page 6-7 of your owner's manual. Let me know if you have any other questions. Thank you.

 

Tricia, GM Customer Service.

[Travism55]

I'm probably being just over worried about my truck, dont know to much about the new ones, driving on the lake wasn't to rough on rough on my truck was it?

[nibael]

Trucks are expensive, it's reasonable to worry. GM builds a tough truck though and they are made to go off road, so try to enjoy it.

[CapitalTruck]

I change my tranny fluid and filter every 25k miles. I have 180,000 miles on it. I have done major too heavy towing for my little 4.8 I can't complain one bit. I would recommend a 25k change interval. Stay on top of it.

[f5fstop]

I'm late to this post, but as a retired GM engineer let me remind everyone trans fluid temps are accumulative Running at a high temp does not immediately destroy the fluid; however it will cause it to degrade faster over a period of time. Hitting 270 for a limited time will not destroy the fluid, but continually doing this will result in the fluid requiring a change sooner than the maintenance schedule states. That's why they have a severe schedule that will require a sooner change.

I left GM just as Dex VI was being released (Dex VI had been out for about a year) so the temps below are for Dex IV and Dex VI is a hell of a lot better. So it is not necessarily accurate for Dex VI, but it gives an example of how fluid will degrade over time with high temps.

 

If you trans temps run at or below the figures shown for long periods of time, the fluid should last for the miles shown with no problems.

175 degrees change every 100,000 miles
195 degrees change every 50,000 miles
215 degrees change every 25,000 miles
235 degrees change every 12,500 miles
255 degrees change every 6,520 miles
275 degrees change every 3,125 miles

 

I also do not believe in just draining a trans and adding fluid. I'm a believer in backflushing the trans WITH TRANS FLUID (never allow someone to backflush a trans with any so-called magical fluid that cleans it). ONLY use the actual fluid that is going to go into it. So, in our cases with the Silverados, backflush with Dex VI. It costs more, but you will remove 99.5 percent of the fluid and replace with new fluid.

From GM's specs for fluid needed to be added for the 6-speed....

 

Pan Removal and Filter Replacement - Approximate Capacity (6L80/6L90) 5.7 liters 6.0 quarts

 

Overhaul - Approximate Capacity (6L80/6L90) 9.9 liters 10.5 quarts (overhaul of trans, TC not touched)

Complete Trans System - Approximate Capacity (6L80) 11.5 liters 12.2 quarts (includes drain of torque converter, all cooling lines and cooler)

Complete Trans System (Heavy Duty Cooling) - Approximate Capacity (6L80/6L90) 11.7 liters 12.4 quarts (includes the external air exchange cooler with HD tow package)

Now, I know some who will drop the pan the first time, replace the filter, and then have a flush done, but my experience when working at GM the filters do not get dirty unless there is already some internal trans damage, and then it is too late anyway.

Personally, since I tow a good size trailer, I will probably have my trans backflushed at around 40K; however, I not only tow a trailer, I also live in a desert and my camping trips require some hefty climbs up and through mountain ranges so the trans temps will increase for long periods of time. And if you do some serious 4x4, it is a good idea to follow the severe schedule in the book which I believe is 45K. (And if you have a 4x4; do the t/case at the same time as the trans.