Trans fluid now or in the spring?

[yobub]

I didn't get a chance to change my transmission fluid before the boat went into storage. I still have access and can change it, but obviously can't run the engine to warm it up.

What are your opinions? Better to change it now recognizing that I won't get all the contaminants or wait until spring when I can run the engine and do a better job?

Trans fluid is a year old, 63 hours (IIRC).

 

[dtfeld]

I'd wait.

Trans fluid doesnt get all the combustion by-products like engine oil, so I don't think there is any hurry, except if you think you have any water in it.

 

[firecadet613]

You're fine waiting. Two years in a row, my oil analysis on my ZF63s has said to leave it and test again next year.

It's too cheap and easy to change... so I just change it out.

 

[fwebster]

For recreational use, with the number of hours we normally run, the reason for an annual fluid change is primarily to remove any moisture that has condensed in the gear case. Given that you cannot run the boat while she is laid up for winter, you sould wait until after a good run (2-3 hours) in the spring so you get the trapped moisture in suspension in the fluid so you get most of that which is trapped in the transmission out with the fluid you remove.

 

[yobub]

Thanks all, that was my thought but wanted to get additional opinions. Spring it is.

 

[Carpediem44DB]

Has anyone actually seen evidence of moisture contamination from normal recreational use of drive oil? I am all about timely service and regular reasonable maintenance but it seems that drive oil should be good for several hundred hours especially if there is a filter involved. I just equate it to our automobiles and trucks. Do you change your ATF every year or at 50,000 miles. I realize that Marine drives and auto/truck transmissions are different in many ways but it seems like this is one of those areas that tend to be over serviced with out really good cause. Really interested in what those of you that have owned and operated multiple boats over decades think about the subject. I am going to replace the filters on mine this year but only because the PO had not had it done since 2019 when he bought it. The oil looks as fresh as new after 110 hours since last changed.
Carpe Diem

 

[techmitch]

Has anyone actually seen evidence of moisture contamination from normal recreational use of drive oil? I am all about timely service and regular reasonable maintenance but it seems that drive oil should be good for several hundred hours especially if there is a filter involved. I just equate it to our automobiles and trucks. Do you change your ATF every year or at 50,000 miles. I realize that Marine drives and auto/truck transmissions are different in many ways but it seems like this is one of those areas that tend to be over serviced with out really good cause. Really interested in what those of you that have owned and operated multiple boats over decades think about the subject. I am going to replace the filters on mine this year but only because the PO had not had it done since 2019 when he bought it. The oil looks as fresh as new after 110 hours since last changed.
Carpe Diem

Two things come to mind. 1.) Is your filter a real filter with media or is it just a screen? 2.) Don't forget thermocycling. Just because the fluid looks good (nice and red or what ever color it looks like when new) doesn't mean it is as good as new. Thermocycling of fluid changes molecular structure and the lube breaks down. Dark fluid is either overheated fluid, contaminated fluid, or both.

 

[Carpediem44DB]

Two things come to mind. 1.) Is your filter a real filter with media or is it just a screen? 2.) Don't forget thermocycling. Just because the fluid looks good (nice and red or what ever color it looks like when new) doesn't mean it is as good as new. Thermocycling of fluid changes molecular structure and the lube breaks down. Dark fluid is either overheated fluid, contaminated fluid, or both.

You are spot on there. What comes to mind though is how oil change intervals for cars has been increased from the old school thought of 3000 miles to over 10,000 miles for modern vehicles. A lot of that is technological advances in engine design and manufacturing as well as the proliferation of synthetic lubricants. I think also there is a component of ecology as well. I know for the aircraft oils anyway, we change at fifty hours or six months by factory recommendation but many studies have been published over the years that show the lubricating properties of the oil does not degrade that fast. The philosophy for the replacement is to remove the corrosive contaminates that the combustion by-products introduce into the oil. We don't have that issue with drive oil.
CD

 

[yobub]

If it informs the discussion, trans is ZF (Hurth) HSW 800 V1. If the answer is "no need to change it", I'm good with that, just trying to follow the mfg. servicing recommendations.

 

[Strypes]

It's not actually "transmission fluid" though right?

The transmissions in my old boat w/ 454s took tranny fluid but the trannys on my 400DB w/ CAT 3116s take the same oil as the engines, I think. Just tying to clarify I understood the mechanic(who did the mechanical survey & pulled samples for analysis) correctly.

I don't do the work(scheduled maintenance & repairs) myself, but I like to be educated.

Thanks!

 

[yobub]

It's not actually "transmission fluid" though right?

The transmissions in my old boat w/ 454s took tranny fluid but the trannys on my 400DB w/ CAT 3116s take the same oil as the engines, I think. Just tying to clarify I understood the mechanic(who did the mechanical survey & pulled samples for analysis) correctly.

I don't do the work(scheduled maintenance & repairs) myself, but I like to be educated.

Thanks!

My transmission uses ATF - Dex III.

 

[Strypes]

My transmission...

ZF?

 

[yobub]

ZF?

ZF (Hurth) HSW 800 V1

 

[fwebster]

We get in trouble when we compare marine engines, transmission and their maintenance with automobiles and trucks. The primary difference with engine oil and transmission fluid or oil is when you run your boat regularly, you develop enough engine heat to "boil" the water out of the lubricating medium and it departs as steam. Then when winter comes, the boat sits there with the condensed moisture corroding away at your very expensive motor parts. The engine may reach 65-75˚ in the daytime and then falls to somewhere in the teens or 20's at night. The next day the process repeats and water droplets form inside both as the engine or transmission gear cases warm up the next day. You car is different………you fire it up and get the engine and transmission too hot to even touch on your way your work or the airport, etc. before you shut it off. For all intents and purposes, just going to the mall or to work probably cooks off all the condensed moisture in the engine, transmission and differential so you don't have an apples and apples comparison or a need to change the transmissioin fluid annually like you do in a boat.

You guys do what you want to do and save $32/year in transmission fluid or hydraulic oil depending upon what type of marine gear you have if you need to save that much on your annual cost…….but ask your self this: Why do transmission makers tell you to change the transmission fluid every 300 hours or annually, whichever comes first?

 

[b_arrington]

It's not actually "transmission fluid" though right?

The transmissions in my old boat w/ 454s took tranny fluid but the trannys on my 400DB w/ CAT 3116s take the same oil as the engines, I think. Just tying to clarify I understood the mechanic(who did the mechanical survey & pulled samples for analysis) correctly.

I don't do the work(scheduled maintenance & repairs) myself, but I like to be educated.

Thanks!

Some marine transmissions use engine oil, some use transmission fluid. Owners need to confirm which is used. My last boat used ATF in the gearcase of the ZF 86 transmission; my current ZF 286A uses the same 15w40 as the engine.

 

[Strypes]

Thanks! Good to know.

 

[Henry Boyd]

Some marine transmissions use engine oil, some use transmission fluid. Owners need to confirm which is used. My last boat used ATF in the gearcase of the ZF 86 transmission; my current ZF 286A uses the same 15w40 as the engine.

And some use old school 90 weight gear oil (grease technically), especially if they’re Swedish.