Puzzling info from GM

2010LTZ4x4 · October 28, 2014

I plan on doing a tranny and frt and rear diff oil change on my next scheduled engine oil change, which I will still do even though GM says under normal driving conditions there is no maintenance required on the 6l80E tranny. I find that odd GM would post that kind of info. They must be really certain that these 6l80 tranny are built proof under Normal driving conditions and while last xxxxxx miles with no fluid change. Here's a copy of it.

Low maintenance:

For severe use, DEXRON VI fluid changes are the only maintenance recommended. For normal use there is no fluid change scheduled.

The Hydra-Matic 6L80 is produced in Ypsilanti, Michigan, Toledo, Ohio and Silao, MX

fondupot · October 28, 2014

Unless you are having tranny issues, no need to flush it. The Dexron ~~is a synthetic.~~ Lasts a long time.

8.1HD/ALLISON · October 28, 2014

I would change filter with fluid. Cheap insurance. Also dont forget the transfer case.

00Silverado4x4 · October 28, 2014

I personally have used the "severe use" instructions on my truck as I do everything with it. So at ~50k, had the trans filter changed, at ~100k I did the diff's, transfer case, trans filter, brake fluid, plugs, blah, blah, blah...

Only thing I have left is to get the coolant and thermostat changed out.

2010LTZ4x4 · October 28, 2014

My truck would fall under the normal conditions, I just believe it's good preventive maintenance to change the tranny fluid after so many years. I'll be doing the fluid and filter change along with the rest of the driveline fluid change on my own. That way I don't have to pay huge money to a garage to have it all done. The beauty of having my own shop hoist.

Colossus · October 30, 2014

Yes it is a good idea because the additives in the oil and other fluids DO break down overtime and thus the protection they offer is no longer there. 50,000 miles is when I like to do it all.

Z45 · October 30, 2014

Unless you are having tranny issues, no need to flush it. The Dexron is a synthetic. Lasts a long time.

GM branded DEXRON-VI is not synthetic. It is made from a blend of Group II and Group III base oils plus the additives package so that would make it a blend.

It does not contain any PAO (polyalphaolefin) which would make it a "true synthetic" Group IV.

All GM has to worry about is if the transmission makes it past the drive-train warranty, after that its your problem. They want you to buy a new truck.

fondupot · October 30, 2014

GM branded DEXRON-VI is not synthetic. It is made from a blend of Group II and Group III base oils plus the additives package so that would make it a blend.

It does not contain any PAO (polyalphaolefin) which would make it a "true synthetic" Group IV.

All GM has to worry about is if the transmission makes it past the drive-train warranty, after that its your problem. They want you to buy a new truck.

Thanks for the info. I always thought Dexron was syn.

Cowpie · October 31, 2014

GM may think that some of their driveline components are bullet proof and need limited servicing, but that is little consolation from what I experienced with my 2013. I always change out all drivetrain fluids/lubes before 3000 miles. I found the rear diff was almost 2 pints low for starters. The transfer case, the fluid looked horrid and the magnetic plug had enough metal filings that I thought it was my cat with it's tail caught in an electrical outlet. I even changed the transfer again at 10,000 miles just to make sure, and it looked normal with very little metal filings on the plug. Not sure what they used in there the first time, but it was definitely substandard. Both the factory and the dealer need to share blame allowing a customer to drive off with a new vehicle and not checking fluid levels like the rear dff.

I wouldn't get all caught up in the group III vs group IV synthetic debate. That was an issue a couple of decades ago, but the differences are minuscule and only measurable in a lab nowadays. The additives that are a part of the fluid/lube/oil are equally as important as the base oil itself. No one seems to talk much about that. And it isn't like some dweeb in a lab coat is concocting some group IV PAO in the back lab. It is made from Ethylene gas, which is primarily derived from natural gas. In other words, it is carbon chained molecules just like any other oil, just a little more uniform, but group III is giving it a run for its money.

And lubes made from whale blubber oil in the 1800's is still, technically, classified as "true" synthetic. But I am quite sure I would prefer to NOT run any of it in my engine or drivetrain.