Synthetic Transmission Fluid Change
 

It was much easier than I anticipated -- changing out the auto-trans fluid. Unscrew the plug, drain, fill. The plug has a magnetic tip and had a generous build-up of grey gunk and shavings. Apparently it did its job.

The rationale is that the synthetic fluid will allow a longer-term service interval, and hopefully less resistance and friction.

The substance of choice is AMSoil ATF (the only synthetic rated for Honda Z1 transmission requirements).

This is merely a drain and fill at 2.9 Quarts vs. the overhaul capacity at 6.2 U.S. Quarts.

CAUTION: BUTT DYNO...

I can't say that the shifts are smoother (purposely tightened), but TC lockup seems to offer more pull (which can be good or bad). The hope is that heat and slicker resistance offer better FE.

Objective data is forthcoming. Over the next few tanks, we'll see if it's worth it...

RH77

lucky!, I have to crack the tranny fluid pan, drain, scrape and reapply new gasket. It's not that hard at all. Lots of tranny's would last soo much longer if people changed their fluid and tranny fluid filter more often than 100k miles.

Good question: $80/Gallon. I put about a quart in my In-Law's Civic that wasn't treated properly by the dealer (way low on the dipstick -- below the low mark) -- and 2.7 more quarts in the 'Teg. I have a tad leftover.

The best I can tell, it's the first change in 133K miles. The drain plug looked untouched. The concern: new fluid can be the "final nail in the coffin" for a weakened tranny -- or new life for a strong one.

Another note: at high-speed EOC, the transmission had a loud whine at 55+ MPH. Now that has disappeared -- no more noise. EOC is definitely hard on the stock tranny -- but it has held up fine so far...

RH77

Mopar might make a deep sump oil pan for you tranny. Features a drain plug to make fluid changes easier. It'd be worth it if you plan on keeping the ZJ till it rusts to pieces.

RH77, with only ~3qts vs ~6qts the tranny can take, you aren't worried that going half with synthetic and half with the original stuff might cause problems/limit potential of the new fluid?

I have thought of this. The problem of an overhaul change is the time and effort to clear it all out (disconnecting the radiator hoses, have an assistance start the car, shift into gear, drain the old fluid out and draw the new fluid into the inflow hose...)

I had the bottle of the stuff for a month and had a quick evening to get it done :o.

The compatibility isn't a concern -- it can mix OK, but you're right, the "syntheticness" total is roughly half. The plan is to order another gallon and change it out again in 30K miles (or the 3rd oil change) -- which should get it up to at least 75%+. Then I'll have another bit to start the process on the Civic (I plan to take over the maintenance on it -- the dealer seemed to drop the ball on fluids -- I'm a bit upset about that and may have a case against them for fraud). It was looked at within 7000 miles and the trans fluid was barely on the stick. The air filter looked like it had not been touched in over 50K miles (the bolts were nearly welded onto the airbox).

I know it's costly for the fluid, but a transmission is too. An argument can be made that a standard fluid change is sufficient -- but that's not exciting :) There's some Scientific Testing effect as well, to see if the FE budges at all. EOC worries me too...but so far, so good. :thumbup: I'm working on extreme temps from bitter cold to boiling hot. It seems like a good investment...

RH77

Considering the noticeable buildup you found, I would recommend at least the next trans fluid change be done at the regular interval, until such time the fluid appears to run clean(er).

I'm happy replacing one tranny pan's worth at every 4K mile oil change. Synthetic, that is. Would work fine for non-synthetic also, I'd think.

I've been changing out one tranny pan's worth of my ATF at every oil change. In my case that's 2.5 qt of the 7.8 qt tranny capacity. Pull the plug, let it drain, replace, check to verify the level next time driving.

I'd already changed over to synthetic ATF before I started the regular changes along with oil change.

My theory is - the owners manual says to change out the ATF at 30K miles. So I change 32% of it approx every 4K miles. After 8 changes (32K miles) I've changed 95% of the fluid. I'm happy with that. The synthetic stuff is pretty pricey, about $6/qt last time I got some. This spreads out the cost so it's tolerable, and gives a mix of old/new fluid.

Before you start thinking how bad it is to be running around with half your fluid older than 15K miles, just remember that waiting to do a full flush leaves you driving with 100% of your fluid with um, how many miles on that stuff?

If I keep the car long enough I might do a full flush after maybe 100-120K miles. But I think it would be fine if I never do that full flush.

The fluid color was fairly red (a dark red), it seemed to be in good shape (not grey or brown) -- but the magnetic plug had its fair share of graphite-colored gunk and shavings. I may take your advice on this...

I change my oil every 7.5K miles, so that's 30K over the 4th change. Still, the stuff is pretty costly, so this next changeout may be it for a while (unless the plug shows a high level of nastiness).

I fear the "flush". I've heard from shops that the flush tends to clean-away gunk that's holding things together -- I know it sounds odd, but I've heard of it from several independent sources.

RH77

Top engineer at Honda talking about Transmission fluid misconceptions.

http://www.youtube.com/watch?v=6PCbdTO97bA

Tranny changes with oil changes, isnt that a bit much? Yes the tranny fluid does see more stress than engine oil, but, and I'm just thinking aloud here, tranny fluid would be build to withstand longer run times?