Transmission fluid

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Lyle

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Jun 26, 2004
114
Hunter Passage 42 Pt Roberts, WA
Time to change the oil in my Hurth 150 transmission. The manual calls for Dextron III ATF which is getting harder to find. Anyone know if you can substitute Mercon V ATF for Dextron III - is it the same thing?
 
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jimg

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Jun 5, 2004
175
catalina 27 dana point
Trans fluid

Dexron VI is the new formula, available in Mobil and other brands. It is better (a synthetic blend) and is backward compatible to transmissions requiring Dexron II or III, as well as Mercon. Your boat transmission has nowhere near the stress, strain, and abuse that an automotive automatic transmission does. It will be more than adequate.
 
Feb 26, 2004
22,997
Catalina 34 224 Maple Bay, BC, Canada
jimg is correct. The trick, though, with transmission fluid is to always get the OLD stuff out first. Anything with Dexron, regardless the #, will work just fine. So will other ATFs, but just don't mix 'em.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
I hear you guys talk about compatibility, but I am always nervous about using synthetic products where the natual product had been used before.

I had a BMW manual transmission that had to be resealed because someone put synthetic fluid where the natural fuild had been before. This is not to say that it will cause a problem, but MAY cause problems.
 
Jan 12, 2006
48
Catalina 25 All Over, USA
Time to change the oil in my Hurth 150 transmission. The manual calls for Dextron III ATF which is getting harder to find. Anyone know if you can substitute Merkon V ATF for Dextron III - is it the same thing?
Wally World carries Dextron III. I'd be hesitant to change to synthetic...be very difficult to be SURE all the old was out before you put the new in.
 

Newbie

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Apr 16, 2010
18
None yet Not yet Saint Petersburg
The synthetic is a far superior product and you can go farther with less. Meaning you won't have to change it again for a long long while.
In a cars trans dextron should be changed every 15 to 20 thousand miles where as synthetic can go 30 thousand miles and still look like new. A far superior product.
But check just the same to make sure it is compatible but I don't see a problem.
 
Sep 15, 2009
6,243
S2 9.2a Fairhope Al
I hear you guys talk about compatibility, but I am always nervous about using synthetic products where the natual product had been used before.

I had a BMW manual transmission that had to be resealed because someone put synthetic fluid where the natural fuild had been before. This is not to say that it will cause a problem, but MAY cause problems.
the original fluid may have been non detergent and the synthetic may have been deterget based hence causing the seals to give up ...the old vw bugs used nondetergent from the factory and people used to change to detergent and when they did it would clean up everything to the point of loosing the sealed surfaces as back then the oil had a lot of parafin and the detergent oil wiuld clean it out exposing only the worn surfaces and the worn seals creating a loss of seal power ......

regards

woody
 
Feb 6, 1998
11,701
Canadian Sailcraft 36T Casco Bay, ME
The synthetic is a far superior product and you can go farther with less. Meaning you won't have to change it again for a long long while.
In a cars trans dextron should be changed every 15 to 20 thousand miles where as synthetic can go 30 thousand miles and still look like new. A far superior product.
But check just the same to make sure it is compatible but I don't see a problem.

Synthetic is good stuff, if you start with it, or use shortly after break in. To convert an old engine from a standard ATF to synthetic could likely result in leaks. There are TONS of complaints of syn leaks on all types of automotive forums. Converting an automatic auto transmission from conventional to syn can be a death sentence unless it is relatively new.

Engine leaks happened to me three times with syn conversions.:doh:Yes, I am sometimes slow on the uptake. Finally got smart and stopped converting cars run on conventional oil to synthetic. Using synthetic in a diesel eng is a false economy IMHO as the diesel oil gets dirty and that is what kills it. Syn gets just as dirty as conventional..

I own one car that runs synthetic, Mobil 1, and I honestly wish it did not as I have seen no benefit.

My local car dealer has a customer with over 800k on an un-rebuilt engine & transmission. He commutes from Portland, ME to Boston, MA. Oil has been changed at Honda's interval with conventional oil. Considering I get rid of my cars before 200k I think I'll be fine with conventional oil..;)
 
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