Amsoil synchromesh in ZF-5

Kevin 007

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I would not try the MTG being a gear oil at a much thicker viscosity. The ZF fluid should be in and around a 30wt and I can't imagine the syncro's would appreciate a 75+ wt oil in there. Syncro's usually grind more so when the trans is cold (thicker fluid) and eases up a bit once warmed up. So in most cases a thinner cold viscosity is what seems to help out syncros.
 

Kevin 007

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Installed MTF in 2, ZF-6's now. I can say the cold shifts have improved slightly, but not as noticeable as the zf-5. However these zf-6's are in better shape/tighter then the zf-5 that I tried. I have always found that the zf-6 is a little notchier to shift then the zf-5. So anything helps I suppose.

Anyways, just an update. No bad effects thus far with either trans.
 

Won24

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So, I'm about to pull my trans to replace my clutch and DMF. I was just wondering, are you still running the Synchromesh fluid? How's it treating you? Will you fill with it again? I called Amsoil, of course they attempted to steer me off of it. No business in their right mind would recommend something the manufacturer doesn't. But I know using ATF in a manual trans is not optimal. I also get grinding if I attempt to shift quickly without rev matching well enough. I'm hoping SMF, new clutch, and proper gear oil will make driving the truck even more of a treat.
 

ROCK HARVEY

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Amsoil makes a synthetic ATF that matches the oil specification listed on my Zf5 transmission tag. Is there a reason you guys prefer the synchromesh? Is it just to compensate for worn synchros? When I finish rebuilding my zf5 I was planning on using the amsoil ATF.
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IDIBRONCO

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The_Josh_Bear

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Amsoil makes a synthetic ATF that matches the oil specification listed on my Zf5 transmission tag. Is there a reason you guys prefer the synchromesh? Is it just to compensate for worn synchros? When I finish rebuilding my zf5 I was planning on using the amsoil ATF.
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MTL is just a dedicated synthetic lubricant for manual transmissions, and while I'm certain that it's ATF based, it has some type of friction modifier or otherwise helpful component that keeps the synchros gripping properly, longer.
So it's preventative and also a better bandaid when you already have a dying transmission. I use the Redline MTL personally but I'm sure the Amsoil is very good, as is the GM Synchromesh stuff that started all this. It's just a better product for the same application. Kinda like synthetic oil vs dino, it's just a better lubricant with better properties and film strength and detergents.
Hope that helps, my synchros weren't in pretty shape when I got my rig and the MTL I've had in it let it run OK for another 150k+. If it's not cold out it still runs fine even in the morning.
 

chillman88

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I'm tempted to put John deere hygaurd in mine. I put hygaurd in my idi plow truck c6 and it loves it I also added a external filter to it

The low viscosity hyguard shifts slightly harder than generic ATF. Could definitely be the age of the transmission showing in my case though. It's not bad, but you can tell a difference in feel.
 

Isaac Ristow

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The low viscosity hyguard shifts slightly harder than generic ATF. Could definitely be the age of the transmission showing in my case though. It's not bad, but you can tell a difference in feel.
I wonder what regular viscosity would be like in one. I have regular cheap atf in mine right now I put it in when I built the truck and was gonna change it pretty early I don't put many miles on it
 

chillman88

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I wonder what regular viscosity would be like in one. I have regular cheap atf in mine right now I put it in when I built the truck and was gonna change it pretty early I don't put many miles on it

I would imagine it would be harder to shift, being thicker. The low viscosity is still slightly higher in viscosity than dex/merc atf.
 

Booyah45828

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Synchromesh has the viscosity of an atf, but without all the additives and frictions modifiers that are present in modern atf. ATf is a neat fluid for it's application, as it needs to be a lubricant, but it can't lubricate so well that the clutches slip when they're not supposed to. I've also read modern atf has things in it that will corrode/eat brass, which makes it a no-no in some transmissions, which is why oems created manual trans fluids.

ZF wanted the light viscosity for their transmissions, which is why they spec'd atf over gear oil, which was the norm in manual transmissions. Gear oils will withstand high pressures better then atf, but if it can't get into tight spaces to lube stuff, it's not going to work as a lube. ATF being thinner will get into tight spots better. MTF will do the same. I put mtf in a lot of manual transmissions and it works very well. I also put it in transfercases too, with no ill effects. In my eyes it's essentially a synthetic low viscosity atf without the friction modifiers for clutches.
 

CDX825

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Amsoil syncromesh is a 5W30 viscosity which is actually quite a bit thicker than standard ATF.

John Deere low viscosity hy gard is about the same viscosity as regular ATF. The regular Hy Gard is around a 5W30/10W30 viscosity.
 

Booyah45828

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Seems to me it's closer to atf then 5w30. Being a filtration nut, you probably know more about oil and the exact specs/viscosity breaks, but pulling the specs from pennzoil's site for kinematic viscosity seems to say something different.


fluid[email protected]°[email protected]°
dex 339.17.8
synchromesh41.69.8
5w30 conventional63.410.5
 
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