What gear oil in 2006 Chevy manual trans?

[Tod74]

Trying to find info for my boss.

2006 Chevy half ton short bed.5 speed manual trans. He wants to switch to full synthetic in the trans. What should he use?

[gearhead1011]

It looks like there are a few different manual transmissions that could be in that truck and they each require a different fluid. I don't think going to a full synthetic is a good idea. Synchronizers in a manual transmission depend on a certain amount of friction to function and synthetics sometimes interfere with that and cause shifting problems.

[traysvega]

NV3500/mg5 or a NV4500/mw3.....

Prob 3500 which takes GM Syncromesh
If by chance its the 4500= its a gm synthetic fluid part no.12346190

IMO No real reason/benifit to stray from the factory fluid.