This is a heads-up based on actual experiences I have had in the very active 2003 SC SVT Cobra "scene". Also, some feedback from Rick at www.amazonracing.com.

It is relevant here because of just published info that the MY04 tranny has replaced the brass syncho rings with carbon material.

The T56 used in the SVT use carbon blocking rings in the synchros - there have been some reports in the field of premature "glazing" and difficult shifting in some cars that used synthetic ATF's and gear oils. I personally witnessed a teardown of a car with only 5k that had this problem - it was also built up and had been ridden hard. But there did appear to be glazing of the carbon material.

We in the trade often refer to a lube's lubricity, which deals with its frictional properties and "grabbiness". The right balance must be struck in a tranny to ensure all the parts work together well - that is why it is often the case that the stock fluid is the best all around, as it was the fluid engineered into the mix, and for which all the engineering studies and forensics are based.

Synoils (or any specialty lube like GM Syncromesh) can have lubricity properties quite different than OEM spec. Sometimes that can be good - sometimes not so good.

This is more of an issue with carbon than brass for one simple reason - carbon material tends to "absorb" lubricant - nrass does not - it is merely coated. The exchange of mechanical energy from the lubricity of the lube is different in each case - the difference may acccount for some of the reporets of preemie ring wear.

I would suggest being very careful before swapping out the stock fluid until some brave soul does and will attest to 10-20k miles of no problem alfresco motoring.

Just a heads up from Glenn, that "oil guy".

 

Several have been used for extended periods without problem, in fact the stock fluid does not do as well as some others in extreme heat. The GM, and especially RL MT-90 do a better job and have been used for a long time. Keep in mind that this is a transmission that has not done a sterling job for owners as delivered (with hundreds of inconsistent repairs for poor engagement and other problems) so the search for improvement, including lubricants started a good while ago.

 

OK, but I was tallking about the MY04, for which there is no field experience I am aware of.