ATF performance when transmission is cold & hot

[Lyondellic]

I have been using Royal Purple Max ATF in my 2007 Civic LX for a couple of months now. For the sake of testing only, I am going to perform a couple of drain/fills with Amsoil ATF this weekend. The RP ATF performs well enough, but the transmission feels a bit notchy when I come to a complete stop. This was not present when the fill was 100% Honda Z1 ATF. I also feel as though the RP ATF tends to make acceleration feel somewhat "sluggish" at times for lack of a better description. That is where my question comes from.

The RP ATF feels great when the transmission is cool. The notchy feeling that I have described above is not present for the first few minutes of operation. Acceleration also feels excellent during the first few minutes as well. This does not make a lot of sense to me. I would think that the issues would be more prevalent when the ATF & transmission were cool, gradually fading away as everything warmed up. The strange thing is that the opposite is true. The transmission feels better when it is cool and the issues manifest after it reaches operating temperature.

Do friction modifiers tend to behave differently when ATF is cool versus normal operating temps? Obviously viscosity will be higher when ATF is cool, but that doesn't seem to play a role in the situation. Surely ATF will perform better at operating temps that when cool.

Any thoughts on this?

 

[MolaKule]

Your ATF is thinning as (like most fluids) when its temp rises.

If this is a manual transmission, next time try a 9.3 cSt synchromesh fluid such as GM Synchromesh or Pennzoil Synchromesh.

 

[Donald]

If your transmission is an auto, I would suggest a cooling line flush you can do yourself to exchange the fluid for Amsoil ATF (great stuff). Its much more cost effective when exchanging expensive ATF. If its a manual not sure why you cannot drain out all the old fluid and add new.

 

[ZZman]

What was wrong with the Honda Fluid? Why not use that if it worked well for you?

 

[Lyondellic]

This vehicle has an AT. Honda Z1 felt OK, but shifts seemed to take too long at times (sliding into gear). The RP Max ATF has a viscosity of 7.4 @ 100°C, which I believe is slightly higher than the Z1. That's why the change in shifting behavior when the RP ATF reached operating temperature didn't make sense to me. If the Z1 ATF has a lower viscosity than the RP ATF, wouldn't shift quality issues be even more pronounced with the Z1 ATF?

The only thing that seems to explain this is an apparent impact on FM performance over the cool to warm temperature range. Maybe I am missing something here?

 

[Donald]

Do a cooling system flush (yourself) and replace with Amsoil. Has anyone on BITOG said anything negative about Amsoil ATF?

 

[unDummy]

Are you 100% MaxATF? or just a couple drain/refills?

You want to play with transmission adaptive programming which is variable for driving style and ATF temp. Shift quality and shift type are manipulated.
You should try a battery disconnect overnight after each drain/refill.

Also, don't rule out the engine. Its power will vary with temp causing transmission to feel different.

 

[thrace]

If an AT shifts differently when hot, it could be there is a mechanical problem with the trans itself. Maybe not just an ATF issue.

Have had some broken AT's. The latest is the notorious Honda Odyssey 2002 5 speed. Shifted the same hot or cold from new until 50K miles. Not much problem when cold at first. Over time noticed gradually increasing slipping and shuddering when warm. Slipped very badly and shuddered violently when hot. Once problems first happened, always worked more normally when cold. And always worked worse when hot.

Not sure what notchy means. (Here is a humorous look at auto tester vocabulary including notchy.)http://ch1.gtchannel.com/AutoNews/index.php?s=quattroporte

 

[Lyondellic]

I performed my first drain/fill with Amsoil ATF this afternoon. The notchy feeling has diminished somewhat. The transmission feels ever so slightly more responsive as well. I will update this post after my 2nd drain/fill with Amsoil ATF. So far results seem to be favorable.

 

[02zx9r]

Not surprising that the amsoil will be MUCH better than the royal purple, not surprising at all!