ZF6-Age old debate

NyCowboy87

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Ok guys since it's a rainy crappy day I've been inside bored as hell which is never good. Been making a list of what I have to/want to do to the truck this spring while I'm waiting for the salt to get washed off the roads. I need to pull the trans and throw a clutch in it so while its out might as well change the fluid. I've searched around Google for over an hour and read of guys using everything from trans fluid, engine oil and gear lube in these things. Does anyone have hard evidence on what is better and what should be used? This trans has a good amount of gear noise to it and I would like to quiet it down if I can do so by just changing fluids. However I don't really want to toast it by running the wrong stuff in it. Truck is usually always hooked to a trailer hauling the horses.


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superpsd

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I had grinding syncros in my Zf5 and a good deal of rollover noise due to the heavier clutch. I overfill ed it with Redline MTL and the grinds are mostly gone and rollover noise is very minimal.
 

superpsd

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Yup yank out the shifter and the ZF5 normally is rated at like 4.5 Quarts and I dumped in 5. Not sure what the ZF6 is rated for capacity. Carefull of the bushings for the shifter trunion shaft as they slip right off easily. I had one slip off and fall into the transmission one time thankfully at a spot needle nose pliers got it out.
 
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I had grinding syncros in my Zf5 and a good deal of rollover noise due to the heavier clutch. I overfill ed it with Redline MTL and the grinds are mostly gone and rollover noise is very minimal.
This ^^^^. I had a good deal of noise as well. I started with just changing fluid and going back with Merton V, that was burnt looking at 10,000 miles, so I swapped to a gear lube, shifted like butter for a day, next day couldn't hardly go from gear to gear without major grinding, next day drained and flushed it, went to royal purple MTL, it seemed fine but wore down very quickly and needed changed at about 7000 miles, so far all oils attempts to over fill, still had rollover. Then ordered some Redline MTL, put it in from the top, no rollover, no grinding, and shifted better than ever. Drained it at close to 10,000 miles when we pulled the trans to do up-pipes for a T4 kit, fluid still appeared good, but I figured since manuals are so Cheap to rebuild, might as well while it's out. So we did, and I went back with the Redline MTL, never had any issues. Just remember, the MTL is not a long service life oil, but absolutely performed better...

I absolutely second calling Jim at LE though, I bet he has something far superior

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m j

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google says it calls for merconV. what are the syncro blocker rings made of? if its old skool brass then they wont be ruined by any oil. the lube pump might not like thick gear oil
 

psduser1

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google says it calls for merconV. what are the syncro blocker rings made of? if its old skool brass then they wont be ruined by any oil. the lube pump might not like thick gear oil
No way I'd run gear oil in a zf.
 

NyCowboy87

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Looking through our oil inventory at work found some sae50 synthetic mtl. We run it in our service trucks that have eaton synchro6 transmissions. Thinking I might give it a try.


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psduser1

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why not?

live life full throttle

god bless america and the farmer who feeds your fat ass

Too high of viscosity. Multiple people-Trans guys, oil guys, the dealer-they all say the same. The clearances are too tight for good oil flow in the zfs. Mercon, etc. is only in the neighborhood of 10-20w.
 

lincolnlocker

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Too high of viscosity. Multiple people-Trans guys, oil guys, the dealer-they all say the same. The clearances are too tight for good oil flow in the zfs. Mercon, etc. is only in the neighborhood of 10-20w.
thats what I thought. just wanted to confirm. thanks man!

live life full throttle

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superpsd

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I'm pretty happy with my switch to Redline MTL. I do not know how many miles this transmission has on it but it may be the full 300K that's on the clock. The syncros were grinding badly as they are worn. I tried multiple types of ATF and all made the transmission noisy and hard to shift. Dumped in MTL and grinds are 90% less often, transmission is quieter. Also shifts smoother especially when cold.
The syncros are worn but it will allow me to stretch out the miles on the transmission for many more to come.
 

gwunter

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I never was a fan of "fixes in a bottle" but Im really tempted to try some of this red line mtl in my m5r2. It's got a pretty rough shift from either direction going in to 2nd, all the rest are good. Now thus isn't an additive, it's a full lube change right?? Where can it be bought, autozone or advance?
 

lincolnlocker

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I never was a fan of "fixes in a bottle" but Im really tempted to try some of this red line mtl in my m5r2. It's got a pretty rough shift from either direction going in to 2nd, all the rest are good. Now thus isn't an additive, it's a full lube change right?? Where can it be bought, autozone or advance?
you might hit up jimdawg185 and try some lubrication engineers products.. it is some badass lube!!

live life full throttle

god bless america and the farmer who feeds your fat ass
 

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