Question ZF 6spd fluid change

[commanderjjones]

I feel kinda dumb asking this, but I've read dozens of threads and hundreds of posts and didn't see it covered anywhere.

I wanna go synthetic (probably RP) on my next fluid change in the tranny and transfer case (front and rear diff' have already been changed). From what I've read, RP synchromax is what I need to put in there, right?

Another question......how do I go about getting all of the fluid out of the cooler? Am I just gonna have to flush all of the old fluid by changing it, driving it several miles, then changing it again or what?

What do you guys think would be a max. safe temp' on the manual tranny? Depending on ambient temp's, I'm usually running around 150 or 160 unloaded and about 180 to 200 when towing. Got it up to about 220 on a long heavy tow once. I assume that since the auto will take those temp's that a manual with withstand slightly higher? I know those temp's are fine, I was just wondering what "normal" would be on the manual tranny and how much heat they will take.

Sorry for all the questions. Your input is appreciated.

 

[Frankenstien]

Not a dumb question.... :-D

I've run either Amsoil synthetic, or Mobile one Synthetic from the get go... I have over 225 thousand on this gear box on the original seals and internals. If you leave the tranny in the truck when you drain then its a little bit difficult to flush the cooler, however there is not a lot of volume in it, probably less than 2 or three cups total. The original fluid from FOMOCO is synthetic so I would not be too concerned about the residual fluid. I am not familiar with RP Synchromax. BTW your X-fer case uses different fluid than the Tranny.

As far as your tranny temps are concerned, you have no worries about burning anything internal, I dont have a guage on mine and have been towing heavy for a long time. I think most of your tranny internal temps is heat transferred from the clutch and engine crank. If the clutch is slipping you would see a spike, 220 is plenty cool for not roasting seals and fluid, I would be concerned if temps were to hit 270 + as thats when the rubber on the seal would start to get gooey. Hope this helps....

 

[copracr]

Do you have a cooler on your manual transmission? What pumps the fluid to it? manuals dont have pumps, right?

I feel kinda dumb asking this, but I've read dozens of threads and hundreds of posts and didn't see it covered anywhere.

I wanna go synthetic (probably RP) on my next fluid change in the tranny and transfer case (front and rear diff' have already been changed). From what I've read, RP synchromax is what I need to put in there, right?

Another question......how do I go about getting all of the fluid out of the cooler? Am I just gonna have to flush all of the old fluid by changing it, driving it several miles, then changing it again or what?

What do you guys think would be a max. safe temp' on the manual tranny? Depending on ambient temp's, I'm usually running around 150 or 160 unloaded and about 180 to 200 when towing. Got it up to about 220 on a long heavy tow once. I assume that since the auto will take those temp's that a manual with withstand slightly higher? I know those temp's are fine, I was just wondering what "normal" would be on the manual tranny and how much heat they will take.

Sorry for all the questions. Your input is appreciated.

 

[Frankenstien]

The ZF 6 Does have a cooler, the pump is built in to the tranny housing. ... drivers side on the forward portion of the housing. the factory cooler is only 3 or 4 coils around 8 inches in length. ZF Company puts tranny pumps on all of their trannies that I have seen. At least the ones that I have looked at on line. if you ever take your case apart, you'll need to remember to line up the drive spline of the gear unit to the pump, if you fail to do this you WILL split the housing.

 

[commanderjjones]

Not a dumb question.... :-D
BTW your X-fer case uses different fluid than the Tranny.

Thanks. It's been a while since I have changed it and that must have slipped my mind. I guess I need to break out my manual before I go purchase fluids.

I'm not sure who makes them, but evidently the Ford lubricants are pretty good and hope I'm not making a mistake by switching to RP. I'm about to hit 300,000 miles and have been using Ford lubricants throughout the drivetrain (except for Rotella in the engine) with ZERO problems or leaks. My truck has been awesome and I brag on it every chance I get. Just replaced the alternator last week......I can't imagine too many vehicles getting 300k out of an alternator. Also still has the original belt.......yeah, I know I'm pushing it and have been carrying a spare for a long time, but I wanna see HOW long it will last.

 

[copracr]

Does anyone know where a guide is for changing the fluid , perhaps with pics? Or if i get under there will it be evident where the drain and fill plugs are?

Also, how much fluid should i get for a change?

 

[commanderjjones]

Does anyone know where a guide is for changing the fluid , perhaps with pics? Or if i get under there will it be evident where the drain and fill plugs are?

Also, how much fluid should i get for a change?

The drain and fill plugs are pretty obvious. The bottom one can't be missed and the fill plug is on the left side of the tranny. They both use a 1/2" drive ratchet for removal. It's been a while and I recommend checking your manual before purchasing it, but it seems like I used 3 quarts.