Synthetic Transmission fluid?

Hi,

I have done a search, but only found one response on the subject. My boat mechanic recommended adding synthetic transmission fluid rather than the usual Dexron III which replaced the Type A fluid that the manual recommends. The synthetic fluid container said it was compatible with Dexron fluids.

The engine is the Universal 5416 16 hp diesel with the Hurth transmission.

The only thread on this subject I could find suggested that synthetic transmission fluid in the Hurth transmission is a good idea as it would allow the transmission to run cooler than regular fluid, and cool is good for it.

Can anyone confirm that this is ok, or give reasons why not to use synthetic. The transmission has been functioning well, and the fluid change was simply part of my annual maintenance. I have had the boat out a couple of times since, and it seems to run same as before, but I don't want to cause any long term damage by using an inappropriate fluid.

Thanks for any comments.

Frank

A marine mechanic I used had also recommended synthetic tranny oil. His view was that it was more stressed than the engine itself. I have a 25XP with a Hurth transmission. I'd be interested in other's feedback.
Regards,
Erich

Erich, did you put synthetic fluid into your transmission, and if so, how long ago? Did it make any difference or cause any problems?
Frank

More synthetic discussion

http://www.ericsonyachts.org/infoexchange/showthread.php?t=4721&referrerid=28

Ah ha. I put "synthetic" into the search box and found this earlier thread. I thought I remembered this from somewhere....


Trivia: if I recall, you need a 17 mm short socket or ratcheting end wrench for the drain plug on the bottom. I cannot see it without a mirror, but can reach under there with difficulty. Swearing will be involved. Bend and straighten a shallow alum. baking "pan" and push it under, with a bunch of absorbent cloth or paper in it for the 10 oz. of red oil that will fall out. Big Fun!


Loren

ATF Oil

Frank,

I just got back from the basement to see what we used. After researching the issue a few years back (I don't recall any my rationale) I decided on "Red Line Synthetic ATF for Dextron II Appliciations" for our 8424 (Universal 24hp/M30) engine.

For the first change we did a couple of quick changes to flush out all the old stuff (who knew how long it had been in there or what it was). The transmission (Hurth) seems to be happy with it, and we've probably got 250 or so hours with it in it.

Thanks, guys for this additional information. It sounds as if synthetic transmission fluid is ok, so we've gone ahead with it, and so far it's working fine.
Frank.

Try Foley Hytork Fluid

I've had good luck with Foley Hytork Fluid. It's pricey but it keeps the transmission cool and gears good. Here is a link

http://www.foleyengines.com/FreeTechnicalInfo/DrDieselShopKinks/MarineTransmissionFluid.aspx

While there is..

While there is no doubt that synthetic is a better product it can sometimes cause older seals to begin leaking. Having had three vehicles that I switched over to synthetic oil on, at about 70-80k, that then began having numerous oil leaks where there had been none. I now use only conventional products in engines that are older. I have never had another oil leak since sticking with conventional oils. If it was new and you changed to a synthetic shortly after break in it is a terrific product but for older seals it can mean the difference between tranny fluid in teh bilge or not..

As for tranny fluid I change it yearly and have never had a single marine transmission failure or issue. I simply place three oil absorbing pads under the tranny, pull the plug, and let er drain. I then clean up any fluid with a strong degreaser and some rags & fill it up.. Takes about 15 minutes start to finish. Trying to suck it out is a royal PITA comparatively speaking and the bilge pads hold the entire contents quite easily..

Changing the tranny fluid yearly is critical on some of the Hurth trannies...

That is an interesting take on synthetics. I have had the opposite results with switching to synthetics on multiple vehicles with high mileage, read well past 100K. I will say that older synthetic oils did have a reputation of leaking after changing over in old seals. The new formulations have apparently fixed this issue. IMHO, if it leaks after changing then is was leaking a bit before and was on its way anyway.

Sucking the oil out is extremely easy IF you do it the right way. I have a Ball jar with 1/8" fittings in the top, with a bit of vacuum tubing and a hand vacuum pump, the Ball jar is a handy catch can. Sucking the trans dry takes less than a minute and there is no cleanup.

RT

I prefer draining through the drain plug which will also drain anything other than fluid which could be a symptom of a future failure. I can fit a 16oz plastic cup under mine on top of an oil pad. I let it drain all day and then refill.

I had a 1990 Audi that had 110k miles on it when I switched to synthetic(Mobile 1). Within the year I started loosing oil. Unfortunately the car was totaled before I could determine the cause. This has always made me doubt synthetics. My '96 Audi only takes Mobile 1 and has since the break in. I am the second owner so having bought the car under that scheme, I opted not to change. My other vehicle uses dino oil and I change it every 3k just as I have on every vehicle I have ever owned(except the Audi)

I may call hurth in the spring to see what they recommend as my tranny is only 3 seasons old.

I admit I'm a bit of a maintenance nut, particularly when it come to lubricants. I primarily drive diesel vehicles, they are picky when it comes to oil change intervals and type of oil, so I believe in and use oil analysis to establish oil change intervals and periodically check on engine health. What I have found is that most of the time changing the oil at 3K is overkill. Oil analysis will indicate the level of wear occurring and allow a safe extension of oil change interval. My vehicles all use a 6K change interval with enough life left in the oil to allow a safety margin.

That said, not every application will benefit from synthetics. One of the main reason I like synthetics is they do allow extended intervals, even with soot loading from diesels. The second benefit is in winter the superior "flowability" of the synthetic allows an engine to crank much faster and start easier. Not a huge deal with most gas engines but a huge benefit with diesels. The increase in cost in synthetics can be offset by the extended interval and also, to be blunt, the extended interval usually allows me to get through winter without lying on the frozen ground servicing the vehicles.

So in a sailboat engine that operates fairly low hours per season and in moderate to warm conditions there is really no benefit to using a synthetic. In a transmission however I think its a good idea. The synthetic will operate at a higher temperature, provide better lubrication and longer life.

YRMV, but synthetics have worked great for me. RT

I bought synthetic diesel engine oil, and synthetic tranny oil from Pep boys. Only a few bucks more than regular oil. I hope that I didn't screw up.

rwthomas1 said:

That is an interesting take on synthetics. I have had the opposite results with switching to synthetics on multiple vehicles with high mileage, read well past 100K. I will say that older synthetic oils did have a reputation of leaking after changing over in old seals. The new formulations have apparently fixed this issue. IMHO, if it leaks after changing then is was leaking a bit before and was on its way anyway.

Sucking the oil out is extremely easy IF you do it the right way. I have a Ball jar with 1/8" fittings in the top, with a bit of vacuum tubing and a hand vacuum pump, the Ball jar is a handy catch can. Sucking the trans dry takes less than a minute and there is no cleanup.

RT

Click to expand...

I should have mentioned that I have a v-drive and it's nearly impossible to get a drain tube to the bottom of the sump. Even with my old M-25's I still never got all of it and drained the rest through the drain plug. I agree with Tim on getting what is in the sump via the plug..

Synthetics are great but I'm still not personally comfortable changing higher hours/miles engines over to it..

The biggest problem in sailboat aux engines, IMHO, is condensation from short run times. Synthetic or conventional makes no difference if you don't run the engine long enough to burn off the start up condensation..

Maine Sail said:

I should have mentioned that I have a v-drive and it's nearly impossible to get a drain tube to the bottom of the sump. Even with my old M-25's I still never got all of it and drained the rest through the drain plug. I agree with Tim on getting what is in the sump via the plug..

Synthetics are great but I'm still not personally comfortable changing higher hours/miles engines over to it..

The biggest problem in sailboat aux engines, IMHO, is condensation from short run times. Synthetic or conventional makes no difference if you don't run the engine long enough to burn off the start up condensation..

Click to expand...

I would agree that trans type and installation are huge factors in how you service them. I have a standard Hurth 100, with only 12oz or so of lube and very easy top access, straight down to the lowest point on the unit with a suction tube, its pretty simple. If I was dealing with a v-drive then things would likely be different. I would think the important point here is that we both know that the trans actually has fluid in it and know how to change it, not the case in many forgotten and neglected boats.

I also agree on the condensation issues. If you are going to run it at least get it up to operating temp and keep it there for a few minutes.

RT

I agree that it's very easy to suck the Hurth dry. I am too tall to fit in the engine compartment, so my daughter has been replacing the transmission fluid since she was 10 years old. She removes the filler cap/bolt, inserts the suction tube and snakes it around until all the fluid is removed, refills it, checks the level, and replaces the bolt. I stand on deck with the suction tank and a beer.

I wish sucking the oil from my Perkins were that easy.

rwthomas1 said:

That is an interesting take on synthetics. I have had the opposite results with switching to synthetics on multiple vehicles with high mileage, read well past 100K. I will say that older synthetic oils did have a reputation of leaking after changing over in old seals. The new formulations have apparently fixed this issue. IMHO, if it leaks after changing then is was leaking a bit before and was on its way anyway.

Sucking the oil out is extremely easy IF you do it the right way. I have a Ball jar with 1/8" fittings in the top, with a bit of vacuum tubing and a hand vacuum pump, the Ball jar is a handy catch can. Sucking the trans dry takes less than a minute and there is no cleanup.

RT

Click to expand...

I wouldn't take the advice of a mechanic. I would contact the technical service group of the transmission manufacturer and talk to their engineers. They are the ones who run durability tests and analyize torque and anti-torque wear on gears and internal bearings.