4L60E "Shouldn`t change the transmission fluid"???

Sort of. You should disconnect the cooler tube, start engine only long enough to pump the pan dry. Then change the filter and clean the pan and magnet. Reinstall the pan, add ~5 quarts of fresh fluid, then start engine and flush fluid as you've described. Top off the fluid afterwards as needed. There's no sense in pouring clean fluid into a dirty pan, flushing the fluid by sucking it through a dirty filter, and then dumping five quarts of "clean" fluid so you can then change the filter and clean the dreck out of the pan. The best way is to drop the cooler OUTLET tube, either at the trans end and then direct the fluid into a drain pan, or at the cooler end (usually easier to access) and use a parts-store length of tubing on the cooler outlet fitting to direct that fluid into the big (20-ish quarts) drain pan. That way you flush the cooler, too. I did this on my 4L60E, took a total of 15 quarts of fluid--ten or twelve is the capacity of the system, and a few extra needed to flush the old stuff out.

Yeah, I remember when 1960's trans fluids were supposed to be "lifetime" fluids. The engineers were crazy-optimistic then, they're crazy-optimistic now. Wishing doesn't make it so.



Change the filter, clean the pan, flush the fluid, top-off when warm. No need for a drain plug on the trans pan if you disconnect a cooler tube and use the trans pump to push the fluid out. A drain plug you don't install, cannot leak or get hooked on something you drive over--a speed-bump, the neighbor's kid, whatever.

 

I like that idea of pumping pan dry...

 

Agreed.

The issue is when to change the filter, and therefore when to clean the dreck out of the pan.

I see no reason to pour clean fluid into a dirty pan, so the new fluid gets pulled through a dirty filter. And then, you pump all the old fluid out...and waste five quarts of fresh fluid when you finally do drop the pan.

Drop the cooler tube. Pump the pan nearly dry, clean the pan and replace the filter...and THEN you pour clean fluid into a clean pan, with a clean filter. Start the engine, pump the remaining old fluid out while pouring more clean fluid in.

 

Crap, I did get the procedure order wrong. I hang my head in shame. Absolutely correct, change the filter first, refill, disconnect the return line from the cooler and keep adding fluid until the fluid coming out looks like what’s being poured in.

 

[QUOTE="Schurkey, post: 3152594, member:

Yeah, I remember when 1960's trans fluids were supposed to be "lifetime" fluids. The engineers were crazy-optimistic then, they're crazy-optimistic now. Wishing doesn't make it so.

[/QUOTE]

Embellishing phrases like "crazy optimistic" & "wishing doesn't make it so" are exactly the words never used by an engineer and as I had bounded the guidance which was very clear it isn't optimistic and not related or relevant to "60's" engineering. This guidance is additionally supported by more rigor and real life endurance testing again straight from the horse's mouth Jim Miller literally working in the harshest conditions at the GM proving grounds in AZ. The other huge assumption implied with those relational 60's statements is fluid technology between 60s to mid 90 or even now is the same. That isn't true - My uncle has a PhD in lubrication and owns LSI. The casual and informative conversations I have had with him do nothing but support the relevance of the current guidance not guidance from the 60's. To completely disregard the guidance of an engineered hydraulic machine from the 90s forward isn't necessarily wise.


Sure, there are always extreme random situations that remain un-quantified leaving people to believe there own pseudo scientific guidance.

To add more towards this and the advancement of engineering, I wonder how my father who is an RV transporter (a former trained mechanic of 20 years as well) has ~ 2,000,000 miles combined on all his F250's (5r110 transmissions) with out 1 drop of transmission fluid changed ever between all his trucks?

Automatic transmissions are hydraulic machines, the fluid technology to avoid sheering breakdown, particle suspension (aka clutch material), heat moderation, and low oxidation is greatly improved when the 4LXX and 4TXX were developed. This fluid is not like motor oil, not even close to being engineered the same. I would argue people insist on applying the need to change fluids like motor oil to hydraulic fluid. Likewise, I did not discuss clutch material or filtration.

The point being, the OP asked about a modern GM transmission not a THM350 or 400. The transmission discussed already had issues (fluid loss) and therefore needed attention, next the question was asked regarding the fluid change guidance.

Both of which has been answered, then there are opinionated responses based solely on experience lacking engineering and scientific support.


Feel free to change fluids unnecessarily and/or on personal conviction when no issues are present or diagnosed there is nothing wrong with this except the assertion that is the correct guidance. It is not.

 

That's a lot of typing

 

I violate this in every way. My '04 Pontiac has 440k miles on the original transmission - I've changed it every 175k or so. According to the old wife's tale that's the worst thing to do (since I wasn't changing at 100k or less intervals) but here I am.

I've heard that some BMW's transmissions are literally sealed - no pan to drop. Haven't seen this myself, but a friend said he needed to pull the transmission and drill/tap a pipe plug into the case in order to do a fluid change.

-Bob C.

 

My 2013 Lexus GS 350 AWD has lifetime transmission fluid. That forum goes nuts over changing the fluid or not. It is worse that a religious battle or, heaven forbid, talking about brands of oil.

The Lexus transmission has no dipstick. There is a port in the bottom of the transmission that you check when the transmission is exactly 160°F. If fluid comes out, let it drain. If none does, add some in the fill port until it does.

Others advocate using a siphon to pull out a measured amount of fluid and replace with the exact same amount of new fluid. Another camp believes you must do this 3 times to get all new fluid in the trans.

I laugh at both sides in that debate. Mine has 60K and I'm not going to screw with it because I won't drive my car enough to reach 100K miles. I've only put 15K miles on it in three years. Another 40K miles would take me eight years. By then it will be a 16 year old car and I'm sure something else will catch my eye before then.

 

I only use .45 ACP fluid. That 9mm is worthless for serious driving.

 

Just drop the pan and replace the filter and top it off... it’s not 100% ideal but it’s a lot better than no oil changes. There is no risk to doing this way beyond that you leave some fluid in the system.

it’s the “flushes” that damage things.

 

Fine. What does Lexus define as "Lifetime"?

Some manufacturers define "Lifetime" as 150K miles. By that standard, my '88 K1500 is early into it's third life.

Wild Guess: The "engineers" and "marketers" who were bragging-up "Lifetime" trans fluid in the '60s were basing that on a "Lifetime" of 60--70--80 thousand miles. So how they define "lifetime" is extremely important.

It is bat-shiit crazy to think that trans fluid is good "forever". We know that the fluid oxidizes, we know it gets contaminated, we know that the volatile parts of the fluid boil-off over time. All that can be measured, it's no secret but it's also not well-publicized.

Explain how.

 

There is no service interval listed at all for transmission as far as the intervals are listed.

 

Yes. Because the fluid is supposed to last the "Lifetime" of the transmission.

But what is the "lifetime" of the trans? I bet they're expecting about 150K, just like ZF.

The whole problem--and therefore my concern--is that these folks are essentially using deceptive advertising, because most people are going to think "Lifetime" is the same as "forever"; when the truth is that the manufacturers have a definite mileage in mind--but they're not willing to tell the consumer what that is. Publicizing the expected lifetime of the trans would defeat their goal--hoping to confuse the consumer into thinking "lifetime" means "forever".

So, for example, a ZF trans goes 160K, it's beyond it's expected life, and to them you're on borrowed time. That fluid is DONE, but the consumer has been told it doesn't need to be changed "for the life of the trans".

The same deal in the '60s; except the mileage limits were different (lower). "Lifetime" fluid is not really "lifetime" fluid--it's the engineers and marketing people finding another way to mislead the consumer.

 

The method you described regarding pumping out the old fluid is fine however many shops do the reverse flush...

The flushing procedure may cause some fluid to move in the opposite direction of normal flow due to eddy currents, which may increase the risk of dislodging debris and causing it to settle somewhere it shouldn't.

 

I always tell my customers that come in with less than red fluid. " If this thing dies because I serviced it, it is not because I did, it will be because you didn't."

 

Lifetime fluid is a marketing gimmick. If the trans fails, then obviously that’s the lifetime of the fluid. Milage doesn’t matter!!

 

Yes I think when they say lifetime they really only care about getting the car out of the warranty period.