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Synthetic transmission fluid

We have heard all about the advantages of synthetic oil. What about synthetic transmission fluid. That stuff is really expensive. Is it really worth the cost?


  • edited February 2010
    It is if your transmission requires it.
  • edited February 2010
    Manual or automatic?

    I am no tribologist, so this is just anecdote and opinion, but I put synthetic oil in the 5 speed manual transmission of a Toyota once. It started getting noisy soon thereafter, and I had to replace all the bearings in the transmission a couple of years later. I went back to conventional oil.

    On my Volvo 245 5 speed manual, I switched to synthetic oil, and a few years later the transmission disintegrated into an unrebuildable pile of metal shavings. I got another tranny from the junk yard and now use only the recommended conventional oil. I have driven another 150k miles on that tranny which had (??) miles on it when I put it in.

    If we are talking automatics, some cars built after 2000 call for synthetic transmission fluid. Though it is not 'permanent' as the manufacturers suggest, it needs to be replaced very rarely, which is good because it is very expensive. I would not spend the money to put it in an automatic that did not come originally with synthetic fluid.
  • edited February 2010
    It's best to go by your OWNER'S MANUAL AS pointed out, some cars require synthetic fluids.If you own a Honda the EXACT fluid specified and sold by Honda is required. Some aftermarket fluids will say that they are suitable for Hondas.
  • edited February 2010

    There are aftermarket fluids that ARE perfectly compatible with Honda....probably made by the same people that make it for Honda.
  • edited February 2010
    I am no tribologist, so this is just anecdote and opinion, but I put synthetic oil in the 5 speed manual transmission of a Toyota once

    I'm not sure about Toyota...but Nissan had somewhat of the same problem....but it had nothing to do with Synthetic oil...

    Certain transmissions from Nissan required GL-4. There is a newer oil called GL-5 which they claim is 100% compatible with GL-4...Well it's NOT. GL-5 eats the Brass Syncro's. GL-5 contains sulfer...GL-4 does not. So people who put GL-5 in their transmissions ended up rebuilding that transmission about a year later. Later Nissan stated in their owners manual and service manuals to NOT use GL-5...only GL-4...GL-5 WAS allowed in the differentials though.

    I suspect that it wasn't the synthetic oil you used...but the wrong kind of oil.

  • edited February 2010
    I forgot to mention that my vehicle is a 2001 Dodge Ram 1500, V8 4 X 4, automatic transmission. I have not checked my manuel lately but I don't remember it saying anything about using or not using synthetic in the transmission. I'd like to try it if it will be better for my trans and not just a waste of money or damaging either.
  • edited February 2010
    I use after marketfluids in my Hondas. I have for quite some time, and I haven't noticed any problems.

    My Civic has aftermarket power steering fluid (Gunk's "Power Steering Fluid for Honda Vehicles"), aftermarket brake/clutch fluid (DOT3), aftermarket coolant (Prestone), aftermarket manual transmission oil (synthetic 10W-30 oil), and aftermarket motor oil (5W-30, usually Prestone or Valvoline).

    The only Honda brand fluid I currently use is gear oil in the differential on a motorcycle that has a shaft drive instead of a chain, and only because I don't know of a readily available suitable aftermarket substitute.
  • edited February 2010
    A number of things can convince people that synthetics can harm engines or transmissions.

    Some time ago, a man claimed he changed to synthetic oil, and it wrecked his motor. It was likely, based on his general tone, that his motor was going bad, so he decided to try synthetics, in the belief synthetics would save a previously poorly maintained motor. It went out anyway, so he concluded synthetics wrecked his motor. He was rather hostile about it.

    The same thing happens on transmissions. When it starts acting up is not the time to suddenly get religion and expect your sins to be forgiven because you use synthetics.

    And, yet as the one example shows, there can be problems in some cases. But, not because of synthetic, but because, as someone said, a wrong fluid was used.

    I sort of believe that using natural oils and fluids, if changed often enough, will indeed give good service. My personal concern is I am convinced engines which have a sludging problem are more likely to run into problems with natural oil. Still, the mostly obsolete 3,000 mile oil change cycle can almost certainly evade sludging, for most drivers. (Except the 2 miles a day to work types.)

    In my case, I have been using Mobil-1 oil and synthetic fluid for some time. I do extend the oil change after lab testing my oil at 8800 miles. That does not mean someone with a different driving pattern can go 8800 miles. But, every so often I drop three quarts of fluid and add three quarts of synthetic fluid, total cost is very low because I do it myself.

    If you, OP, are happy with what you have been doing, then there may be no reason to change. If it ain't broke, don't fix it.

    By the way, some people do not think synthetic oil is any good. We had a man who insisted that a placebo effect convinced people it was good. Hohohohahahaheeheehee.
  • edited February 2010
    Mike & Whitey; thanks for the comments. An aftermarket fluid has to say on the can that it meets Honda spec, that's what I was getting at. The aftermarket Dexron that I use in the Toyota and Nissan does not carry that label.

    P.S. It is not so much who makes the fluid, but to what spec it is formulated.
  • edited February 2010
    One way to evaluate whether something is expensive is to compare it's cost to the total cost of owning the car. Synthetic fluid is virtually nothing compared to the cost of buying a new car; or installing a new motor or transmission.

    My dad used to say, "penny wise and pound foolish." It was interesting to watch him, because he was the most penny wise and pound foolish man I knew in my life. Good man, but he would get so wrapped up in some small item, he'd let the big things whiz by him.

    In the Fifties, someone bailed our hay and left the bales on the ground, and we'd have to muscle them onto the wagon, 100 bales at a load. Sometimes we'd see black clouds coming from the West, and were frantically trying to get as many under the roof as we could. He'd stop us, carefully sweep a few cents of chaff into a basket from the wagon, while a couple hundred bales of hay were about to get soaked.

    Keep your eye on the big picture, as well as the small items.
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