Dextron ATF is not for the manual transmission.

Type F ATF is the fluid recommended. Or Straight 30WW oil if temp range never below 20.

Ssynthetic fluids NOT meeting factory spec and any additive in an Overdrive will cause problems if the fluid does not meet the Type F specification. It happens in winter without your knowledge.

Use Redline Racing ATF(type F) instead of the MTL Gear lube if you want to go synthetic.

IMOP, unless you race, drive 1000 miles a day, contantly haul heavy loads uphill, etc for extrame use, the cost is not worth it since changing regular Type F ATF every 50,000 miles will get you 200,000 miles further for the same cost and same reductin in whatever you are worried about.

Duane