Engine/Transmission (1998.5 - 2002) Synthetic 6 speed lube

[Texas Diesel]

As posted here, I drained my OEM fluid from the transmission and put in synthetic RP Synchromax. This oil is used in other synchronized transmissions with no problems.



This transmission deserves a better lubrcant than the stuff they fill it with. Attached is a picture of the jellied OEM fluid, and I have a FastCooler and PTO filter. It would have been worse without them.



300 miles later here is my impression: Not a single gear grind and the gear shifts definately have a better feel. Due to the arrival of a cold front, I cant compare oil temps directly to see if it runs cooler like the diff did when I switched it to synthetic. However, comparing the difference in *F between the transmission and Diff I believe the transmission is noticeably cooler. I will know for sure when I tow my TT.





Synthetic motor oil will work but I didnt want the detergents and dispersants that are in motor oil so I kept hunting for a synthetic lubricant that was formulated specifically for a synchronized manual transmission.



I also put it in my transfer case, which used to grind, now it will engage 100% of the time with NO GRIND.



The link the the Synchromax site is listed below, thanks Dane.





I'm thrilled with it so far.



Disclaimer: It is not OEM oil and has the potential of causing warranty issues, but the OEM fluid failed in 22,000 miles and something better is needed in IMO.

 

[Dane]

Hey Tex,

I'm following your quest closely after seeing your 5600 picture



Here's the link to the Synchromax-



http://www.royalpurple.com/retail/retailpdfs/synchromax/synchromaxps.pdf



Keep us posted!



P. S. Thanks for the Dana 80 PDF...

 

[Texas Diesel]

update:



200 mile trip today, max temp (transmission) was 150* @ 93*F ambient. A normal temp would have been 180*F with the OEM fluid.

Read diff ran 160*F and engine (oil) was 210*F for the record.



I'm impressed, my wife said it was smoother shifting as well.



Thanks for the link.