I've been a long time lurker and been using the helpful guides as well as the Helm Inc. factory service manual to maintain my wife's 2007 Fit Sport AT for the past few years.

Finally getting caught up on maintenance on it and just about done once I finish the ATF drain and fills. First D&F came at 72k which was a little too late but transmission hasn't had any major issues other than pressure switch troubles that dealers won't toubleshoot under the 100k powertrain warranty.

I'm doing 3x drain and fills with 100-150 miles apart from each other. I'm doing the 2nd today and the last probably this weekend or early next week. Using DW-1 right now, but wondering about any opinions on how these Z-1 specified transmissions are holding up on DW-1 in the long term. I know it seems hit and miss on the short term side of things but can't seem to find any comments on anyone with 10k+ put on their GD automatics after switching over to DW-1. I know DW-1 seems to be holding it's own in DW-1 spec MY 2011+ Honda's. But what about Z-1 spec transmissions?

I've been debating on doing the 3x drain and fill with the DW-1 to clean out any gunk, then either running that and just doing 1 D&F every 10-15k for a while; or just after 500-1000 miles of DW-1, do a flush at the transmission cooler lines with Amsoil signature series ATF and run that. I'm also open to Redline D4 on this one as that is what I run in the transfer case and power steering of my 2010 F-150 5.4 6R80 4x4. I just seem to come across more comments about Amsoil multi vehicle SS ATF than Redline D4 regarding Honda's.

I am changing the in-line transmission filter during the 3rd drain and fill also.

Fresh DW-1 left, old Z-1 right

 

I'm actually debating on switching to AmSoil's ATF this next fluid replacement.

I've been running DW1 since about 61k miles and currently have just over 113k miles on the vehicle at this time. The last 20k miles included some autocross events.

I do like how DW1 doesn't break down as soon as Z1 along with allows for very smooth shifts as well. Though I am really curious if there are any benefits to running AmSoil's Signature Series ATF as I have yet to find a technical break down of DW-1 that I can understand and compare the two ATFs.

 

I know the amsoil SS multi vehicle is a little thicker than the z-1 and has seen good reviews over amongst the people with problematic transmissions in Odysseys that didn't like dw-1.

The amsoil being mostly group IV base stocks with small amounts of group III for additive carriers, should be significantly more shear stable, resist heat oxidation, and be a all around better platform for a long term atf compared to a syn blend or possibly marginal full syn of dw-1. I've never seen exact % of what base stocks on dw-1.

The only thing amsoil's atf is lacking is the friction modifier packages that Honda uses in z-1 and dw-1. They have their own blend. Could be a good thing or bad thing. I would prefer a fluid that didnt allow so much slip between gears and actually firm up the shifts. Less slipping between gears, firmer shifts, and lower temps for a healthy transmission. Amsoil is suppose to firm up the shifts on a lot of the z-1 transmissions compared to fresh z-1 or dw-1. Haven't really heard any reports on the 07-08 at fits though....

I know a lot of satisfied amsoil atf users and it comes highly recommended for transmissions that get abuses. Just like redline.

You would lose whatever cold weather fuel economy you gained with dw-1.

So dw-1 is holding up for you? How's the fluid looking on drains or flushes? Have anything to monitor trans temps? I keep forgetting to try my datalogger if it is able to see trans temps and/or pressures.

Just did the 2nd drain and fill tonight. 145mi on the 40% dw-1, 60% z-1 and it still looked rough. Didn't smell as burnt and finally had some sort of red tint lol small improvement but not much. Maybe the next one will be better. If the next drain and fill doesn't improve the smell, I'll be hitting up the Honda dealer for a couple more quarts of dw-1.....

 

That sounds good so far regarding AmSoil! I'm not too concerned about fuel economy since I autocross and plan on supercharging my A/T Fit.

I haven't ever noticed a real change in the shift quality since I started using DW-1... ESPECIALLY after I did two DW-1 drain and fills (47k and 61k) get as much of the old Z1 out as possible. Z1 would have a noticeable difference in shift feel around 25k miles into its life (for me), with DW-1 I have yet to have that issue... though I do replace my fluids at pretty much Honda's half life for their fluid intervals.

Also noticed that there is very little "gunk" on the ATF drain plug when replacing fluids, even with autocross days. I'll be changing out the inline filter this next round as an extra precaution. The fluid doesn't smell burnt at all and still has a pretty distinctive red tint to it as well BUT again, I do half life intervals which is about 15k each replacement.

I'm a bit curious about mixing either 2 AmSoil SS ATFs and 1 DW-1 or vice-versa to help the transmission withstand the S/C and the abuse from autocross.

 

http://www.amsoil.com/shop/by-product/transmission-fluid/automatic/signature-series-multi-vehicle-synthetic-automatic-transmission-fluid/

Take a look at their taxi study they ran. Granted it's not a Honda transmission.

Amsoil tech line recommends not mixing if possible. It is compatible however. I was considering doing the flush process via the cooler lines to switch.

That is very good to hear on the magnet being fairly clean. Dumb question..... Have you checked to see just how strong that magnet is and how strong a new magnetic plug is? I checked earlier tonight and the one in our 07 was very weak compared to the ones on my Harley. I'm wondering if the heat cycle has weakened it or if it is that weak new.

 

For a supercharged application, is there any tuners available for these model year fits that allow you to tune the transmission and bump up shift pressures for a tighter lockup? I would be worried about large power adders causing the tc to slip a little too much before lockup.

Are you running any sort of engine/trans tuners now? I run an SCT X3 on my F-150 with a tune from 5 star tuning. The transmission adjustments with the SCT was like night and day with towing or offroading at WOT. Much firmer shifting with higher shift pressures and lower temps. Not as comfortable of a ride for the person who wants a CVT type ride of almost hidden shift points, but I hate slippage (heat).

Just curious, running autocross, what sort of oil and oil filters are you running for how long? Ran any used oil analysis after some events? I know in high heat, stop and go with lots of idle time, these engines seem very low wearing with good synthetics and just wondering how they look turning high rpms routinely.

 

I would stick with the Honda trans fluid you could also change the trans filter

I am about to try the 0w20 purol oil bisimoto recommended just to see if i notice any difference from the royal purple.