JHZR2
Staff member
Hello,
I am well aware that the follow-on dex fluids are backwards compatible, and thus very acceptable for use in older applications, but there is a school of thought in the MB world that the older mechanical ATs that are specced for, say Dex II or IID may do better on a dex II spec fluid than a Dex III or VI. I am not sure if I attest to this or not, but am looking for thoughts.
My thought is that the Dex II fluid had a different viscosity and frictional characteristic than dex III, Dex VI, etc. Sure, some of that was built in for shear, but at the same time, there are differences. Now, for a modern AT, say one that was from the late 1990s, Im sure than Dex VI will do perfectly in place for Dex III, and I do use it. But modern electronic transmissions are smart enough to account for all sorts of parameters.
Older mechanical ATs are not that smart. Therefore, they are designed to a point based upon the spec fluid that is supposed to be used in there. In applications where the AT might be smart enough to adapt, it is no issue, and in applications where getting 20k, 50k, 100k before a rebuild is due is one thing... But I'm talking MB diesels, where after 150k, another 200-300k of trouble free miles is expected.
redline sells a Dex II fluid, which IMO is sold for that very reason. They say it themselves that the D4, etc. are far more widely usable fluids, but there certainly is a reason to sell it.
MB has spec sheet numbers for various ATFs, with the exception of 236.3, which is an undyed type A ATF for PS service, they follow somewhat along the dexron procession. They make a difference between applications with electronically controlled lockup clutches, and mechanical ATs. Some of the fluids are back-specifyable, others are not.
Still, it may be the same point of Dex II vs III, or III vs VI, etc., they are more than good enough for reasonable service going forward, in most vehicles.
But again, the fluids are designed for ever smarter and more complex ATs, but if they do not have the same friction and viscosity characteristics, they may NOT be ideal for a mechanical-controlled and operated AT.
Something like redline Dex II may be ideal, as it will be shear-stable, oxidation-stable, etc., yet maintain the characteristics of dex II that the AT was designed to.
Any thoughts???
I am well aware that the follow-on dex fluids are backwards compatible, and thus very acceptable for use in older applications, but there is a school of thought in the MB world that the older mechanical ATs that are specced for, say Dex II or IID may do better on a dex II spec fluid than a Dex III or VI. I am not sure if I attest to this or not, but am looking for thoughts.
My thought is that the Dex II fluid had a different viscosity and frictional characteristic than dex III, Dex VI, etc. Sure, some of that was built in for shear, but at the same time, there are differences. Now, for a modern AT, say one that was from the late 1990s, Im sure than Dex VI will do perfectly in place for Dex III, and I do use it. But modern electronic transmissions are smart enough to account for all sorts of parameters.
Older mechanical ATs are not that smart. Therefore, they are designed to a point based upon the spec fluid that is supposed to be used in there. In applications where the AT might be smart enough to adapt, it is no issue, and in applications where getting 20k, 50k, 100k before a rebuild is due is one thing... But I'm talking MB diesels, where after 150k, another 200-300k of trouble free miles is expected.
redline sells a Dex II fluid, which IMO is sold for that very reason. They say it themselves that the D4, etc. are far more widely usable fluids, but there certainly is a reason to sell it.
MB has spec sheet numbers for various ATFs, with the exception of 236.3, which is an undyed type A ATF for PS service, they follow somewhat along the dexron procession. They make a difference between applications with electronically controlled lockup clutches, and mechanical ATs. Some of the fluids are back-specifyable, others are not.
Still, it may be the same point of Dex II vs III, or III vs VI, etc., they are more than good enough for reasonable service going forward, in most vehicles.
But again, the fluids are designed for ever smarter and more complex ATs, but if they do not have the same friction and viscosity characteristics, they may NOT be ideal for a mechanical-controlled and operated AT.
Something like redline Dex II may be ideal, as it will be shear-stable, oxidation-stable, etc., yet maintain the characteristics of dex II that the AT was designed to.
Any thoughts???
