High mileage Fluid Change?

[Wylie_Tahoe]

is that trans fluid is high with detergents and to replace all fluid could shock the system and help damage the plates.

Motor oil has detergent, with diesel being higher. It would be like capturing half the used engine oil during an engine change, and putting it back in with a few qrts of fresh new engine oil.

I also saw a couple times on here that the 4L60 trans is good for about 160k before likely having to plan on replacement.

I guess he's 10K past expiration, so no harm doing a flush then

 

[OR VietVet]

Motor oil has detergent, with diesel being higher. It would be like capturing half the used engine oil during an engine change, and putting it back in with a few qrts of fresh new engine oil.

If you are going to quote me at least use the whole sentence so the context is correct.

"I believe what I have heard many times before is that trans fluid is high with detergents and to replace all fluid could shock the system and help damage the plates."

I said what I had heard. I have never tested or investigated it myself and that is why I said I had "heard" many times. No biggee though. If my assumption is wrong, I can live with that. If I know something to be a fact I will say so but if not I just share what I have "heard".



This is a direct quote from Advanced Transmissions:

The detergent or cleaning agent is used because transmission fluid is not changed as often as engine oil. Therefore it becomes necessary to have plenty of detergents or cleaning agents in the automatic transmission fluid so the contaminants stay in suspension and don't congregate in one area.

And another:

Since automatic transmission fluids contain detergents and help fight sludge, some enthusiasts add a small amount to their motor oil prior to changing oil as a way to clean accumulated deposits and dissolve sludge. ... First, the detergency, or cleaning power, of ATF is much less than motor oil.

Now about motor oil:

Detergent additives, dating back to the early 1930s, are used to clean and neutralize oil impurities which would normally cause deposits (oil sludge) on vital engine parts. Typical detergents are magnesium sulfonates. Corrosion or rust inhibiting additives retard the oxidation of metals inside an engine.

 

[Wylie_Tahoe]

The detergent or cleaning agent is used because transmission fluid is not changed as often as engine oil. Therefore it becomes necessary to have plenty of detergents or cleaning agents in the automatic transmission fluid so the contaminants stay in suspension and don't congregate in one area.

As stated, engine oils have detergents. so contradiction right there. Second, trans fluid is not changed as often because its not subject to the carbon particulates (burned gasoline), hydrocarbons (raw gasoline) and moisture, that engine oil is subject to.

If a walk around the block causes a heart attack, you were destined for a heart attack anyway. If your trans has soo much build up that fresh clean fluid causes an issue, you were already having issues.

 

[OR VietVet]

I posted about engine oils also having detergents. It is right there.

Whatever makes you sleep at night is fine by me.

 

[SnowDrifter]

Ok so let's cut through this

1. Trans fluid doesn't have hardly any detergents. There's no varnish to clean in a normally operating transmission. They do, however, have a ton of dispersants to keep particles in suspension and stop them from settling out in areas like the valve body

2. The trans fluid change blow up thing isn't a myth, just misunderstood and misattributed. It has nothing to do with shocking a system. Much more a case of revealing a problem that's already there. As I mentioned above, trans fluid is really good at keeping particles in suspension. Now what happens, is if you have a high mileage transmission with worn clutches and shit fluid, it still works because the fluid has enough particulates and debris in it to allow worn out plates and bands to grab. If you change the fluid to something with the appropriate lubricity, you'll then discover that your trans was worn out. Nothing was broken or shocked, merely a problem revealed.

So how do you decide if you can change it?

Start your rig, drive it around, pull your dipstick and drop the fluid onto something white and non absorbant. The emissions sticker works great for this. See a bunch of visible floaties? Don't **** with it and start saving. Does it look relatively free of debris and just dark/dirty? Go ahead and change it out

Tldr bad fluid wears out items, bad fluid masks worn items, good fluid reveals worn items.

 

[SnowDrifter]

Also because I know someone will comment on it, yes your trans has particulates in it. No the filter doesn't do anything. It's extremely coarse and designed more as a glorified screen to protect large chunks from ruining the pump than it is a fine filter.

 

[Sdp1234]

Start your rig, drive it around, pull your dipstick and drop the fluid onto something white and non absorbant. The emissions sticker works great for this. See a bunch of visible floaties? Don't **** with it and start saving. Does it look relatively free of debris and just dark/dirty? Go ahead and change it out

I’m going to check this out on Thursday. I’m almost afraid to test it... ignorance can be bliss.

 

[SnowDrifter]

I’m going to check this out on Thursday. I’m almost afraid to test it... ignorance can be bliss.

LOL I'm a numbers guy, I just follow the data. Seek to understand why something is the case and ignore basically all of the old wives tales. When you understand a system, you can better propose a solution to any given problem.

I think having an answer is better, personally. Though I'll admit I also do a lot of my driving in nowhere. I'm pretty breakdow-averse. When I consider that I'll have north of a $600 tow bill plus need to find a hotel and hope that someone stops by to get a ride to cell reception, I opt for the knowledge is power approach. It gives you a definitive decision tree.

If it looks OK, then you can change it with some peace of mind. If it looks like ass, then you know to make arrangements in advance to either sell the vehicle or replace the transmission. Either way it's a win win, but you'll never have thar "what if" floating in thr back of your mind wondering if you can take your rig on a trip or not.

 

[treehan77]

Good advice. If it has particulates visible, I’d drive it till you need a new transmission, could be quite a while if you do t mess with it.

 

[SnowDrifter]

Good advice. If it has particulates visible, I’d drive it till you need a new transmission, could be quite a while if you do t mess with it.

Yep. And unfortunately there's no straight answer when you're at that point. Basically just playing the waiting game to see what fails first. Valve body / pump / gears / bearings /whatever. Just set aside some cash so when it does happen you're not running around like a chicken with your head cut off trying to figure out how you get to work. Could be 5k, could be 50k.