Trans Fluid Question

[Phatman]

My son just did a fluid change in his S10 truck.
He told me he changed the trans fluid as well. He told me it looked to him like ATF fluid in the 5 speed gear box and he replaced it with gear lube as per the book he had bought.

I asked him if he had checked the owner's manual, to which he replied NO.....

I looked in the owner's manual which said ATF fluid. My question is what harm may have been done in two days of driving and how the two fluids will mix if he drains the gear lube and replaces it with ATF again?

 

[The Radius Kid]

Don't worry about it,just change it.

 

[FlyinGN]

since gear lube is generally thicker and will really get like mollasses in the extreme cold (more so then ATF) you may get some hard shifting and gear clash in cold weather. I would drain it and put what is specified back in.. There should be no capibility problems with trans fluid and gear oil.

 

[Phatman]

Thanks for the responses, that's pretty much what I had thought but figured I'd ask anyway....

 

[GNVAIR]

Most late model gear boxes use fiber lined blocker rings for smoother shifting. The fiber is similar to that on the clutches of an automatic transmission. The fiber add a friction coefficient to the cone of the gear to help slow the gear down for the smooth shifts. Most late models specify either Dexron or GM type synchromesh. Replacing the ATF with gear oil will ruin the blocker rings with the quickness. Always use what the manufacturer specifies.