HST Oil Change: Fact or Fiction?

[DieselBound]

Hi,

I know many of today's cars do not have the need to change automatic transmission fluid. There may not even be a dipstick to check level?

I just bought another 5 gallon pail super UDT for my Kabota tractors. I now have enough to change the HST fluid in both tractors which I will do.

But I'm wondering after the first initial HST fluid change, which I think is important, if it's really necessary to keep changing the HST fluid at the recommended Intervals.

My recollection is that the fluid that comes out of my HST looks about the same as it did when it went in new.

What do you guys think?

Auto manufacturers specify "lifetime." When you read the word "lifetime" substitute: "warranty period."

As noted, lots of things don't have ready drains and fills on them. Rear differentials in trucks (and cars) for example. I know that my old Ford F250 diff fluid is supposed to be "lifetime," but they also say that if you run in a bunch of water that you will need/want to change it. Lots depends on conditions, on the environment you're operating in. For example, folks talk about racking up a lot of miles on their transmissions, yet one could rack up a ton of miles with minimal shifts occurring. It's the number of cycles and under what conditions: lots of cycles under a lot of stress will expedite the end of life of a piece of equipment.

50 hr servicing is mostly meant to ensure that production artifacts are purged. In theory the filters should deal with all of it, but to be on the safe side fluid change is promoted (the fluid may be under a bit more stress due to tighter tolerances [friction]).

bobistheoilguy.com is a great site.

 

[newbury]

If he does it right at 50 hours, how "dirty" can the fluid be, it's still new???"

Mine was as clean as what I put back in.


There is far too much obsessing over oil.

Change it, don't change it, it's going to be alright, either way.

From my point of view that first fluid/filter change is to get all the junk out they left in at the factory. I've seen a lot of pictures of metal shavings and particles found on the first fluid change.

 

[IslandTractor]

There is far too much obsessing over oil.

Change it, don't change it, it's going to be alright, either way.

Totally agree.

 

[IslandTractor]

From my point of view that first fluid/filter change is to get all the junk out they left in at the factory. I've seen a lot of pictures of metal shavings and particles found on the first fluid change.

I understand that concept but have you ever had your automobile transmission fluid changed at 1500 miles after "break in"?

 

[LD1]

As an example, my '14 Honda Odyssey has dumb transmission that can only be drained about 30%. The required service is to drain and top off, drive for a couple of days, drain again, drive again, and finally do a third drain and fill. Supposed to be good for 90K miles, I believe.

Almost all automatics are that way. Accumulators, clutchpacks....and the big one.....the torque convertor hole a good bit of fluid that dont drain with the pan removed.

 

[ray66v]

From my point of view that first fluid/filter change is to get all the junk out they left in at the factory. I've seen a lot of pictures of metal shavings and particles found on the first fluid change.

The metal shavings everyone gets all excited about, are trapped in the sump, either by the suction screen, or the filter. Rendering them harmless.

They are not circulating in the system.

I will change the filter, and pull the screen and check it. But, I will never dump fluid out with 50 hours on it again.

And, manufacturers are starting to go that way with their recommendations.

 

[vsteel]

The metal shavings everyone gets all excited about, are trapped in the sump, either by the suction screen, or the filter. Rendering them harmless.

They are not circulating in the system.

I will change the filter, and pull the screen and check it. But, I will never dump fluid out with 50 hours on it again.

And, manufacturers are starting to go that way with their recommendations.

The problem are the metal shavings you can't so easily see, not the large ones you can. The sharp edges can cut through filter material and get through. It is particles in the 20um range that do a lot of damage, you are not going to see those with a naked eye.

I have also rebuilt several automatic transmissions from people who said they don't need to change the fluid.

People not doing maintenance is why I don't buy used tractors or vehicles.

 

[ray66v]

The problem are the metal shavings you can't so easily see, not the large ones you can. The sharp edges can cut through filter material and get through. It is particles in the 20um range that do a lot of damage, you are not going to see those with a naked eye.

I have also rebuilt several automatic transmissions from people who said they don't need to change the fluid.

People not doing maintenance is why I don't buy used tractors or vehicles.

Automotive transmissions do not have anywhere near the level of filtration a HST has.

Everyone is free to do as they feel necessary.

But, the fact is, you can NEVER get all of that stuff out, no matter what you do.

I don't see all the threads on TBN about oil related engine failures, and oil related HST failures, to support the hysteria.

 

[ovrszd]

I agree.

I think the strong opinions on this subject are to reinforce the decisions made. Regardless of direction. Human nature at it's finest. Fact is somewhere in the middle comfortably disguised.

 

[IslandTractor]

[QUOTE="ray66v;]I don't see all the threads on TBN about oil related engine failures, and oil related HST failures, to support the hysteria.[/QUOTE]

That's an important point. There are many hundred HST tractors represented on TBN. Hydrostatic transmission failures are rare.