By on April 9, 2012
TTAC Commentator 70Cougar writes:
Dear Sajeev:

My wife has a 2005 Odyssey with 50,000 miles.  To date, we’ve had no problems with the transmission, but I keep reading about how the transmission on the Odyssey isn’t cut out for a vehicle that heavy.  I’ve been contemplating getting a utility trailer for it (although, shockingly, my wife isn’t too hip on having a utility trailer in the driveway) and, in the course of my research, I’ve found that a transmission cooler is recommended if you’re going to haul a trailer. Is it worthwhile to install a transmission cooler even if I don’t get a trailer?  Is there any downside to transmission coolers (e.g., the trans runs cold for too long)?

My wife has a 5 mile commute (10 miles round trip) and we hope to keep the van at least another 5 years.

Sajeev answers:

Before we start, it’s time to change your transmission fluid.  The reason is twofold: transmission fluid has a finite lifespan, and it will die at the mere sight of a utility trailer attached to its minivan home. I love minivans for their efficient use of space and command seating position, but their transaxles are never good enough.

I think every minivan needs the largest external transmission cooler possible behind the front bumper.  That is almost as important as regular fluid changes.  If you plan on towing anything, carrying enough people/cargo to make the rear springs sag, and/or live in a climate that’s brutal on transmission fluid temperatures, both are mandatory. I’d consider annual transmission fluid changes on any minivan that tows on a regular basis, at highway speeds.

A downside to transmission coolers?  Not that I can think of. Because transmission fluid gets far hotter than engine coolant (hence why many tranny coolers are just a heat exchanger inside the engine radiator) the odds of being too cold aren’t a big concern.  But if you aren’t a Houstonian like yours truly, maybe you will need a radiator block-off pad for your front bumper…in the Yukon Territory.

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37 Comments on “Piston Slap: If you must tow with a Minivan…...”

  • avatar

    My Hyundai XG350 has an external cooler, I was glad to see it there behind the grille. I used one for years on my C4 in an old car, I can’t recommend them enough.

    • 0 avatar


      One point I want to stress: you want the biggest aftermarket cooler possible when you consider towing with some non-truck type of vehicle.

      And while most new trucks are super butch and over done, the older models could stand a tranny cooler upgrade if you want to tow on a regular basis.

  • avatar
    Mark MacInnis

    Here, let me get your address, mate, so I can send you in advance the condolence card for when that Oddy’s tranny grenades on you.

    There, that’s done.

    • 0 avatar

      I know three guys who bought those model Odysseys and paid $10,000 more for them than I did with my GM minivan. Each of them had to replace the transmissions in those Hondas at $4-5,000.

      If you want to keep that thing, you will need a transmission fund for when it blows. It’ll cost you at least twice what it would cost to replace a domestic minivan’s transmission.

    • 0 avatar

      I slapped a cooler on my 2000 Ody as soon as it came home from the dealer. Between that and an annual drain and fill (super easy on the Honda) I got 120K without any transmission issues before unloading the beast in favor of the far superior Sienna. Note that there was a lawsuit and a slightly extended warranty for the Odyssey trannies of a certain vintage, due to their lousy lubrication design and high failure rate. (Not sure the settlement covered 2005’s.) It came out in the proceedings that the failure rate at 100K was 9%. While this is certainly not a good percentage, I think Mopar would have killed for it at the time.

      Summary: do the cooler, and drain/fill annually.

      Aside to Vanilla: the Odyssey was worth $10K more than a GM mini when I sold it too…and worth $10K more every day I drove it in between. Not that I’m a hardcore Japanese fanboi: I’d recommend a new Mopar today over the Ody or Sienna, based on powertrain, ride and price. Too bad GM quit the game instead of trying to improve. I guess the good news is that used Saturn Relays are really cheap!

      • 0 avatar

        Except the problems with the ultradrive during the 90’s were minor compared to the oddy. Many of the mopars had incorrectly marked dipsticks, resulting in the use of the wrong fluid. Many times it was only a bad or loose ground strap. One other issue that was pretty minor was the solenoid pack could clog. Many of them could easily be cleaned, in the case that it couldn’t a new unit only cost 160 bucks.
        The oddy on the other hand suffers problems because the trans design as a whole is junk, the lubrication system is poorly designed, which results in 2nd gear burning out because of fluid starvation. Here is a list of trans problems reported by honda, chrysler and toyota minivan owners. It covers problems reoprted per 1,000 owners from 2001-2009. Note that the mopar minivans have slightly fewer reported problems than the toyotas in most years, though it’s close. They both have fewer complaints than the honda by far.

    • 0 avatar

      I disagree. My Oddysey towed a long flat bed trailer loaded with three dirt bikes, and/or a street bike and two dirt bikes, and/or two street bikes, for two years, with no trouble at all. Piece of cake. The max load my trailer carried was 1500 pounds – within the posted allowable towing capacity – I had no transmission cooler no trailer brakes – all I added was a hitch and wiring for the trailer lights. Took it on several 1000 mile trips = from ohio to vermont last summer. From ohio to the catskills the previous summer. We ran the highway all day at 70+ mph, averaged 17 mpg. smooth runs plenty of acceleration. Watch your tongue weight – my trailer was built so that there was weight on the tongue (axel is behind center of the bed) – the Oddysey suspension was a bit challenged if I loaded a heavy bike on the front of my trailer, I needed to keep the big boys set back so part of the weight above or behind the axel so the weight on the tongue was not excessive.

  • avatar

    Okay… so perspective from the guy who works at a Honda dealership.

    The gospel from Honda says you may tow with the 2005 Odyssey, but if you do, install trans and steering coolers.

    BTW… older 1999-2001 Odysseys had a lot more problems than the ones made in the last few years. I have one customer with a 2007 well in excess of 250,000 miles and that tranny is still going strong. Just sayin’….

    • 0 avatar

      Is it not true that Honda also says that visually-confirmed placement of a tow hitch on your Odyssey without the presence of both the Honda-recommended Power Steering AND Transmission fluid coolers invalidates your respective warranties? Not that the OP’s 2005 model vehicle is under warranty, but it’s worth noting. It’s also worth noting that the 3rd-gen Odyssey has also had a reputation for grenading power steering pumps.

      My 2006 Odyssey has an aftermarket tow hitch that was on the van when I bought it, and near as I could tell was nearly brand-new hardly used as the first major deluge we drove through caused the halfa$$ed wiring to short (spliced into the brake lights instead of using the Honda-specific adapter kit). My van doesn’t have the upgrades to the power steering and trans coolers. The only thing I’ve used the hitch for is toting a luggage rack, but without air bags leveling the rear end I can’t imagine towing anything larger than a few trash cans with relative success.

  • avatar

    Let me see if I have this right:

    -My wife needs the Odyssey to get to work every day.
    -The commute she drives means that the Odyssey should work for many years if not abused.
    -I know that this vehicle has a weak trans mission to begin with.
    -Knowing all of the above, I want to add to the transmission strain by pulling a utility trailer.
    -I don’t have a good place to store a utility trailer.
    -If pulling a trailer grenades the transmission, I will have to replace it for thousands of dollars, plus rent a car so my wife can continue to work.
    -I can rent a pickup or Home Depot truck for a few bucks on the rare occasions when I need a utility trailer.

    70Cougar, listen to your wife.

    • 0 avatar

      Oh, that reminds me: next time, we need pics of the Cougar.

      <<<points to my avatar for justification<<<

    • 0 avatar

      “-I don’t have a good place to store a utility trailer.”

      There’s a solution to this one:

      I own one. It comes as a kit, and putting it together would be a weekend project, even for people who are relatively handy. But it folds up in to a corner of the garage.

  • avatar

    If you do flush the transmission fluid, be sure to use only Honda’s special sauce expensive transmission fluid.

  • avatar

    The Odyssey already comes with a transmission cooler. Unless the OP is planning to transport iron ore in his utility trailer it’s unlikely that the occasional use of such a light duty trailer is going to make any difference in the longevity of the Odyssey’s transmission. As a former 2nd gen Odyssey owner with a blown transmission at 125,000 miles, I would recommend changing the fluid no more often than what Honda recommends for “severe” duty. More often than that and you’re wasting your money. The 2005 transmission clutches were beefed up, but the design still sucks. Your transmission could go out at anytime whether or not you upgrade your trans cooler or change the fluid more often. In other words, if you own an Odyssey you must come to accept that your transmission could fail at any time and that it is beyond your control. The OP might want to reference the Serenity Prayer.

  • avatar

    Trans coolers, their hoses, and clamps can all leak at inopportune moments. Those items all also become new victims of road hazards (rocks and other debris) and front-end collisions (after which you might have otherwise been able to drive away safely). A front-mounted cooler can also be plumbed wrong quite easily. You need to consider flow routing such that the liquid-to-air heat exchanger (the new cooler) is after the liquid-to-liquid heat exchanger (in the radiator) flow-wise for hot weather (and perhaps the opposite for cold weather). The new cooler should also be plumbed so that it doesn’t invite air pockets. One way is to have the fluid enter at the bottom and exit out the top, to assure the cooler is always flooded, and NOT trickling downward. Another option on many cars (not sure of this one) is an aluminum finned pan. Generally speaking, a cooling-type pan will not leak any more than the OEM pan (maybe less) and it isn’t as likely to be the cause of a transmission failure as a front-mount add-on.

  • avatar

    Do not pass go.

    Do not collect $200.

    Do not put added strain on a Honda 5-speed automatic transmission from the mid-2000’s.

    End of discussion.

  • avatar

    I recently purchased a Catera. Now, before you start hooting at me with jeers and catcalls, it had 57k one verified owner miles (1998)and showed like new. There is no transmission dipstick and Opel claims “lifetime” fluid life. What has been the public’s experience with these claims? The car cost $2850. I’d welcome any input.

    • 0 avatar

      I had a 98 A8. Those also came with “lifetime” fluid. Their definition of lifetime was apparently around 140k miles under easy to average service. That’s as long as the average 5-sp ZF would last. To check it, you would have to pull a 17mm allen plug from the pan bottom and somehow see over the top of a tube. To fill it, (after the usual pan R&R) you would follow a complex process of engaging certain gears while up on the lift while pumping fluid in, until fluid poured out of the fill hole. Altogether a very unpleasent messy, time consuming process. That car, much as I loved it, cured me of Audis – at least those out of warranty.

    • 0 avatar

      I hope this doesn’t sound snarky, but that engine in the Catera is much more likely to grenade than the transmission. I do like the Catera though, and it was a pleasant driving car the couple times I’ve driven them.

  • avatar

    The problem with Honda’s V6/5AT combination isn’t necessarily load (because it was cacking in Accords and TLs as well as the Oddy), so the cooler might not help if your transaxle is going to fail. It’s a defect, and one you really want to check for the presence of before Honda’s secret warranty runs out.

    That said, Sajeev’s advice about a tranny cooler is a good one, as is the recommendation to watch that fluid. Any big (>3500lbs, which is not just minivans these days) transaxle-equipped car should have one, minivan or not, towing or not. I’m a front-drive apologist, but I really do question whether or not vehicles this large wouldn’t benefit from some kind of design re-think. I mean, front-drive is brilliant in, eg, the Honda Fit, Mazda 5 Scion iQ. I’m not completely sure it’s such a hot idea in a 4000lb minivan: you’re asking a lot from the fluid, bearings, filters, etc, and not giving it much space to work in.

    • 0 avatar
      George B

      Not sure about the Honda V6/5AT, but my Accord with V6/4AT never had burned transmission fluid or other signs of excess heat. It’s problem was there was no filter that could be changed without removing the transmission. I wish I’d installed an external filter and replaced the fluid every 2 years.

      I had fairly good luck having my Honda automatic rebuilt at a local shop that gets lots of experience rebuilding them. The transmission design is inadequate to the job, but it’s a fairly simple design to rebuild and the shop gets lots of practice.

  • avatar

    When I bought our 2011 Odyssey (with the 5 speed – not the new 6 speed), I specified that the ATF cooler would be added (it is one of three parts of the towing package – the other two parts being the wiring harness and the tow hitch itself). My dealer thought I was nuts but was happy to take my money. I sleep better knowing this trans has a better chance for a longer life.

    We might eventually put on a hitch, but I don’t anticipate doing a lot of towing – maybe for a bike rack. However, the van gets what I call “heavy taxi duty” plus lots of cold starts (DC urban grind).

    On the 4th gen (2011+), Honda does specify an ATF cooler is required for towing. I believe the ATF cooler is the same design for the 5 speed and 6 speed; slightly different location for the 6 speed due to hoses in different spots. Also, I intend to do the drain and fill since there is no drain plug on the trans.

    The Odyssey forums are a great resource – as Sajeev often suggests, find the most-used forum for your vehicle as other owners likely have discussed and been through the trials and tribulations you are facing.

  • avatar

    These don’t-tow-with-a-car-transmission blogs always seem to focus on minivans, with little mention of midsize CUVs like Highlander or Santa Fe. Does this mean the CUV trannies are holding up better in the real world, or are they merely getting a free pass in the media? If Mr. Karesh is out there perhaps he can chime in on this.

    • 0 avatar

      Good question. As the owner of such a CUV, I suspect they carry less weight up and down the road in the real world than minivans do.

      Ours has carried a full load of passengers (6 or 7) only three times in six years.

    • 0 avatar

      Well, not all minivans – just the Hondas. Their record of crappy trannies precedes them. But like Civics – no matter how poor their reliability, folks are just lining up like lemmings to plunk down thousands more than necessary. Nice racket Honda has there, right?

  • avatar

    My auto tranny cooler is bigger than your cooler…..

    Nyah nah nah nah nah.

  • avatar
    Educator(of teachers)Dan

    Does anybody still offer “towing packages” on anything but BOF vehicles? Do those packages still contain stiffer springs and external coolers?

    If the answer to both of these questions is NO, then what the heck is this country coming to?

    • 0 avatar

      My Escape came with a factory towing package. It’s a unibody car based on the Mazda 626 platform, but jacked up to make it look like an “suv”.

      Most minivans have towing packages, and they’re unibody cars.

      The BOF thing is a myth, at least for any trailer under about 3500lbs, according to the rather conservative manufacturer’s marketing propaganda. My Escape is rated to tow 3500lbs (it’s own weight!), as are most minivans — with towing package. As always, the real concern with towing a load is a) balancing the load for a proper tung weight to prevent sway and all manner of bad things, b) stopping the load, and last and least c) the health of the drivetrain.

      My Escape V6 is way overpowered (200hp in a 3450lb vehicle), and accelerating with a load is roughly he same as accelerating uphill – so I’m not worried the health of its drivetrain. What I am worried about is having the tail wag the dog if I’m actually towing that 3500lbs. Balance and trailer brakes should address that but, since I’ve actually experienced this (when towing with my Ranger back when I didn’t know what I was doing), I’m still leery of it happening again (and it’s the kind of deliberate and methodical worry that’s good for safety).

  • avatar

    I am guessing most people who think ‘a utility trailer is just what I need’, have never backed up with a trailer. A short trailer (the kind favored by most people for utility trailers) is hellishly difficlut to back up a driveway.

    If you need a pickup truck get a pickup truck.

    • 0 avatar

      Yeah, backing up a little trailer is a pain in the ass, especially when you can’t see it.

      But, if you need to haul stuff once a month during the summer and commute the rest of the time, a three quarter ton truck (we can’t buy new compact trucks anymore) is just the wrong tool for a job. And hauling around that extra ton of steel (literally) doesn’t serve any purpose most of the time, except making the damn thing hard to park in parking garages and metered spaces.

      A family vehicle w/ towing package + trailer is a much better fit for this kind of use case.

      If you do “truck stuff” every day, or even every week, by all means, get a truck. But I haul large objects once a month (at most), and I park in tight places regularly, so a an F-150 or Silverado would just be a bad idea. I’d love to own a Ranger again, but I can’t justify it anymore, because I wouldn’t use it enough justify the driveway space, much less the expense to really fix one up.

  • avatar

    I get so tired of people thinking you need a pickup to carry things. When I moved to Mexico, I hooked a five by eight foot covered trailer to my 2005 PT Cruiser and dragged it sixteen hundred miles to my new home. No problems with the car, no problems with the trailer. The idea that you have to have a pickup to do any trailer towing is ridiculous.

  • avatar

    Towing a little lightweight utility trailer short distances is a non-issue. It is no different from having 5-6 people in the car, even with 1000lbs on the trailer. You won’t notice it, and neither will the car. Change the fluid using the severe service schedule and call it good. The transmission may grenade at 123K instead of 125K, who cares?

    From the previous responces, you would think the OP is planning to tow a 10Klb boat across the Rockies. Sheesh. And backing up a small trailer is hardly rocket science – add corner flags. I’ve had a little 4X8 utility trailer for a decade, just the ticket for hauling crap to the dump or home from Lowes. No insurance, no inspection, and registration is $14 every other year. I’ve towed it with a variety of cars, from an ’02 Golf TDI to sundry Saabs and Volvos.

    • 0 avatar

      You are correct, towing a small trailer with around 1,000lbs. would be about the same as a load of passengers with a little bit of luggage. If he actually hauls stuff frequently enough to need a trailer but doesn’t have much space for one in his driveway then he would be better off with a small engined pickup. If he doesn’t haul stuff frequently then maybe he would be better off renting a truck from Home Depot the few times that he does need one. I think it’s only 20-25.00 for 2 hours.

      • 0 avatar

        The Home Depot rental truck may not be there when you need one, nor is it handy for other than getting stuff from Home Depot.

        A small engined pickup truck needs to be maintained, registered, insured, and will cost far more than a $500 utility trailer for something that is reliable.

        My trailer has needed its wheel bearings greased once or twice, and I think I have replaced a tailight bulb on it once. That is it for 11 years of use. No insurance (covered by my regular car policy), registration is $14 every other year. I use it 10-12 times a year. I have the folding version another poster mentioned, takes up minimal space when not in use.

      • 0 avatar

        I see what you are saying, but in this gentleman’s case it looks like he may not have much space for the trailer in his driveway, that was why I made those suggestions. I meant that he could trade the minivan for a smaller engined pickup, saving space in his driveway. Dunno the mpg of an oddysey, but a smaller engined truck should be close in mileage.

  • avatar

    Original poster here. Busy week and missed the entry. Thanks for all the input.

    Update–my dad bought a 5×8 utlility trailer to haul ATVs for hunting. He keeps it at my house and my wife is cool with it. We have a third parking spot next to our two car carport, one of life’s simple luxuries. He has a Passport with a transmission cooler (I wonder if the Passport trans is any tougher than the Odyssey’s). You guys have put the fear in me about destroying my transmission. If I do any towing it would local and light duty. I’m off to change my fluid and put in a cooler. I’ll have to think about the risk/reward of towing with the van.

    By the way, I ruled out a pickup because of the cost purchase, maintenance, insurance, and annual registration.

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