Is Honda AT Fluid Really DEXRON?

it's all 5606 based hydr fluid. honda should work on most fluids rated for it's specs but honda can add or adjust the ratio of additives specifically for it's cars but mostly it's quality control. that fluid has to be hydraulic fluid, wet clutch medium & lubrication. manual is a lubricant only & is a whole different situation dealing with bearing type, gear facing & viscosity. in the interest of warentee & quality control it leans you toward using fluid exceeding the specs like the better brands vice using a cheap generic that barely meets the specs. there were 2 types. f type for fords & dextron II.

I have an Accord, and looked into this when it hit 30,000 miles, looking for the 'best' product to flush and refill my auto transmission. What I remember of the process is that original Honda ATF is *not* simply Dexron repackaged, but it is a Honda formulation that is similar to Dexron-II. Not Dexron-III, which has some different detergents, friction additives, and viscosity/temp curve.

A mechanically-inclined friend that I looked into this with who has an older - 'modified' - Accord, told me his manual actually said something about using Dexron-2 when ATF is required and "genuine Honda ATF is not available," but that he'd never put obsolete Dexron-2 in anything - so I would repeat to NOT use Dexron-2; Just sayin'. It is obsolete, does not have the stability nor the viscosity control at elevated temp's as newer formulas.

That being said, my local Honda service dept. was sure that the newer formulation (Z-1?) that Honda 'developed' is better than all older fluids for whatever reason, and now recommended for all Honda automatic transmissions regardless of age (well, except CVT's, of course). Lo-and-behold, the newer manuals like mine note that for temporary need, use Dexron-3 when ATF is required and "genuine Honda ATF-Z1 is not available." So, I take it that Dexron-3 and the newer Honda ATF-Z1 fluid are directly compatible, but Honda has added some friction modifiers and/or other additives (reduce foaming, inhibit corrosion, the usual) to their Z-1 as well as those for specific viscosity or 'slipperiness' numbers they were after. They also warn that the system should then be flushed and refilled with genuine Z-1 when available, as if typical consumers EVER flush and refill their transmission oil. You could probably get the same or similar results by beginning your refill with one of the lube-add products like Lubeguard or even the Duralube or Slick-50 stuff they sell at Walmart.

I am hazarding an EWAG, here, but I reason out of this that there may also be some additives, such as detergents, in the generic Dexron-3 or newer Dex-4/6 products that may not be tested or fully compatible over time, wear, and higher temperatures, and which Honda decided to leave OUT of their formulation. Honda never releases publicly their detailed specs - and won't, to protect their dealer network profits on Z-1 ;)

Now - to wrap this up: I followed a tip from my hot-rod-loving friends and went with a fully synthetic ATF from Redline {quick search gives me this LINK } that they used in their modified Hondas. I flushed and changed out the engine oil with a fully synthetic as well. No issues once the adjustment typically present after an ATF flush was over, and seemed smoother than new after a month or so.

Why synthetic? It's pretty easy to look up the temperature issues - if the temperature of any petro-based ATF gets above the 220F part of the viscosity curve, the fluid starts to break down. Every 20F higher, and you have a rapidly decreasing number of miles before it cooks from pink to brown and metal pieces get so hot that things start wearing quickly. If this happens and your tranny gets really hot forget it (just trade in the car under Uncle Obama's cash-for-clunkers deal?). Synth has higher film strength as well, and is smoother in really cold weather.

btw - A quick search for 'synthetic ATF for Honda' brought up this one, too: RoyalPurple ATF

Have fun!

Thanks to all who replied especially those with detailed knowledge of AT fluid specifications. You have convinced me to stick with the Honda fluid by explaining it is a better product and specially formulated to Honda's specifications. I was inclined to do that already but wanted confirmation that I was not wasting money by buying a generic fluid at a huge mark up.

Dennis Waller

I had an '83 Accord for many years (like 20). The HONDA shop manual specified Dexron II, so that is what I used. In 230,000 miles I NEVER had any transmission problems.

Bill

I happen to have a bottle of the Lubegard. The bottle stated that the product will enhance Dextron/Mercon ATF to perform like Mercon V. Also will enhance Dextron/Mercon to perform like a highly friction modified (HFM) ATF used in Honda, Toyota, Chrysler and all other applications that require a highly friction modified ATF, except Ford type F and CTV applications.

I have only one vehicle that requires a HFM ATF. ( A big Dodge van) I have not had any wear problems to date. I have only 92,000 miles on the truck, so I can neither praise, nor blame the product. I used it only on fluid changes to maintain the warranty. Now I just use it because it is still on the shelf.

If I had a choice, I would use nothing but synthetic if Honda would allow it. Good luck.