Six speed trans life expectancy

KARNUT · February 22, 2019

Something is up because that is the polar opposite of what I have experienced with my vehicles and most of my customers. I've been a tech for 20 years and I have owned GM vehicles (primarily LS and LT vehicles with 4L60 and 6L80 transmmissions) since 06.

I have had friends that somehow burned up motors and transmissions at low mileages and there has always been a reason. There are cases where bad things just happen. But you've had several things happen that aren't typical. Really sucks.

One of my friends was on his 3rd 4L60 trans in his avalanche by 99k miles. I knew him well, he was the type that drove like a grandpa everywhere and I bet he didn't go past 20% throttle 99% of the time. Yet he's blowing through transmissions before they are even due for fluid changes. After nearly a couple of years of me wondering why I was riding with him one day pulling his boat, we're going up a half mile long hill pulling a boat and the truck is struggling it's ass off and he's just driving along. I asked are you "gonna down shift or at least put it in tow mode?", he said why I never have before...

Meanwhile I beat the living dog shit out of my truck, had it tuned and the rev limiter raised to 6500 rpm and I just hammered it everywhere all the time, when I sold it with 191k miles the trans was still mint. Same with my camaro. Had it tuned, bolt ons, big 3800 stall, trans went 190k being just beat the **** up every single day. Some transmissions don't like grandpa driving, a lot of them slip the clutches at light throttle and it wears them out fast. Talked to a builder about this and he said his brother drives like a 90 year old woman, uses only redline trans fluid, and goes through transmissions.

If you keep the fluid changed in the engine and trans, keep the temps right, and keep them from slipping a lot, they will last a long time.

All that being said, sounds like you've had some bad luck.

Every one of my trucks that I could tune I used 50 percent TM. I raised the shift points and max RPMs and ran them hard. Never had a problem.

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Jacoby · February 22, 2019

These trucks can run at 195* trans temps all day long year after year. Today’s trans fluids don’t start to break down till you hit the 225-250* range.

SARNCAN · February 22, 2019

I drive a 2016 5.3 2wd, 3:42. Its a great truck, absolutely no issues at 67K. Well maintained and I stay on top of recommended fluid changes.
In south Texas the temperature in summer driving concerns me as far as long term trans durability. My gut feeling and common sense tells me to run cooler and eliminate the thermostat and bring the operational temps below the 195 degrees. Am I missing something? And I understand the synthetic fluid improvements and its ability to handle heat. But again, One of my questions, did Chevy program the TCM to alter shift points based on temp? And, by eliminating the thermostat will that in itself be detrimental in the long run? I've received mixed advice from several respected mechanics regarding the removal of the 6l80 thermostat.
And along that advice, the Dealers service writer advised against adding an auxiliary Transmission air cooler.
And, another thought concerning operational cool temperatures. On first start up, considering the 10 second to 3 minutes before driving the trans temp is ambient. So how is the concern of operation during low temperature a concern to the internals?
Advice from superior knowledge, PLEASE.

If you install a cooler, you can get a thermal Bypass to insure good working temp in cold weather as well as good protection when it is hot out there.

https://www.oregonperformancetransmission.com/product/LNG-49201.html

https://www.oregonperformancetransmission.com/product/LNG-4739P6.html

The other alternative, is just to flip the factory thermal valve of which it will reduce maximum reaching operating temp

diyer2 · February 22, 2019

A friends dad had a stick shift Toyota pick up.

Lugged the hell out of it all the time.

It required more maintenance than a properly shifted truck.

Mainly spark plugs and it used oil.

Silverado-Hareek · February 22, 2019

On 2/21/2019 at 9:33 AM, diyer2 said:

So you're saying you got a bad trans and engine?

Possible.

Yep. Google the oil consumption issue on the 2007-2010 model years and also google the forward sprag snapping issue on the 4 speed transmission from that timeframe. The transmission issue was linked to a bad batch of parts that affected Silverados, Tahoes, and Suburban. The oil consumption issue....well by now everyone knows about that.

Silverado-Hareek · February 22, 2019

40 minutes ago, 00pooterSS said:

If you keep the fluid changed in the engine and trans, keep the temps right, and keep them from slipping a lot, they will last a long time.

All that being said, sounds like you've had some bad luck.

Yep did all those things. Oil changes every 3,000 miles. Transmission fluid change by the dealer at 50,000. Differential and transfer case fluid changes at 75,000. At 80 whatever thousand miles......snap. Forward sprag in the transmission broke clean in half. The good news is it was only a $2500 repair job instead of a full replacement. By 90,000 miles, i was burning a quart of oil every 2,000-3,000 miles so the dreaded oil consumption issue. At that point it was out of warranty so my options were to keep adding oil until eventually the engine needed to be replaced, or unload it. So i traded it in for my 2014. 2007-2009 was just notoriously terrible years for GM. 2010 started to get better...my buddy did have to get his engine replaced at 60,000 miles in his 2010 Sierra. I would say rather we didn't have bad luck as much as you guys just had good luck haha

Sierra Dan · February 22, 2019

Sorry to hear that Kooper.

Did you have an extended warranty?

Its a shame that there were no seemingly bad symptoms before it went belly up.

Or hopefully whomever you purchased the truck from was not hiding something.

00pooterSS · February 22, 2019

1 hour ago, KARNUT said:

Every one of my trucks that I could tune I used 50 percent TM. I raised the shift points and max RPMs and ran them hard. Never had a problem.

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Yep, keeping TM in play is a major part of keeping them together.

00pooterSS · February 22, 2019

1 hour ago, Jacoby said:

These trucks can run at 195* trans temps all day long year after year. Today’s trans fluids don’t start to break down till you hit the 225-250* range.

Yep. And a lot of people smarter than me have written that oil needs to be at at least 140 degrees to protect properly. So running around at low temps isn't good either. Around 200 is no issue.

00pooterSS · February 22, 2019

49 minutes ago, diyer2 said:

A friends dad had a stick shift Toyota pick up.

Lugged the hell out of it all the time.

It required more maintenance than a properly shifted truck.

Mainly spark plugs and it used oil.

Yeah I see cars all the time that are driven that way that just seem to have more issues than you would think.

00pooterSS · February 22, 2019

41 minutes ago, Silverado-Hareek said:

Yep did all those things. Oil changes every 3,000 miles. Transmission fluid change by the dealer at 50,000. Differential and transfer case fluid changes at 75,000. At 80 whatever thousand miles......snap. Forward sprag in the transmission broke clean in half. The good news is it was only a $2500 repair job instead of a full replacement. By 90,000 miles, i was burning a quart of oil every 2,000-3,000 miles so the dreaded oil consumption issue. At that point it was out of warranty so my options were to keep adding oil until eventually the engine needed to be replaced, or unload it. So i traded it in for my 2014. 2007-2009 was just notoriously terrible years for GM. 2010 started to get better...my buddy did have to get his engine replaced at 60,000 miles in his 2010 Sierra. I would say rather we didn't have bad luck as much as you guys just had good luck haha

Crazy you had all those issues. Sounds like just pure bad luck. I've had excellent luck really. I've done things to motors and transmissions that most say cannot be done and they took it like a champ for years..

Burning oil is becoming increasingly common with newer valvetrain tech and it sucks, but I'm not gonna replace an engine over it. Especially when the lower mileage ones are doing it too. However I'll say a quart every 3k or so isn't terrible at all. Almost every car I ever had has used around that much..

KARNUT · February 22, 2019

Yep, keeping TM in play is a major part of keeping them together.

Before tunes in the carburetor days a good B&M shift kit in the transmission would feel like 50 percent TM reduction. Anymore feels abusive.

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Grumpy Bear · February 22, 2019

Not true. 160F gives about peak protection. With the factory thermostat a winter day can take 100 miles or longer for the transmission oil to reach 190 F. People that drive 20 miles to work never get the box above 100 F. 135 - 175 F is good.

200-250 F? No need to run a transmission that hot. I've posted the heat charts for this topic several times. Wont do any good to post them again. (Motor oil FYI 175-195 F in the pan).

Doesn't matter 'what it can take'. Mobil 1 will tell you there motor oil 'will take' 500 F. How about it, any takers?

2 hours ago, 00pooterSS said:

Yep. And a lot of people smarter than me have written that oil needs to be at at least 140 degrees to protect properly. So running around at low temps isn't good either. Around 200 is no issue.

That is not a lubrication issue. Could have changed oil every ten minutes and not avoided that one. Ouch!

2 hours ago, Silverado-Hareek said:

Yep did all those things. Oil changes every 3,000 miles. Transmission fluid change by the dealer at 50,000. Differential and transfer case fluid changes at 75,000. At 80 whatever thousand miles......snap. Forward sprag in the transmission broke clean in half. The good news is it was only a $2500 repair job instead of a full replacement. By 90,000 miles, i was burning a quart of oil every 2,000-3,000 miles so the dreaded oil consumption issue. At that point it was out of warranty so my options were to keep adding oil until eventually the engine needed to be replaced, or unload it. So i traded it in for my 2014. 2007-2009 was just notoriously terrible years for GM. 2010 started to get better...my buddy did have to get his engine replaced at 60,000 miles in his 2010 Sierra. I would say rather we didn't have bad luck as much as you guys just had good luck haha

Grumpy Bear · February 22, 2019

2 hours ago, KARNUT said:

Before tunes in the carburetor days a good B&M shift kit in the transmission would feel like 50 percent TM reduction. Anymore feels abusive.

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Ever use the Transgo shift kits?