I ordered manual transmission fluid online recently, but ran into a little trouble. I ordered 2 bottles of GM Synchromesh Friction Modified online and when I opened the package, one bottle was the Friction Modified and the other bottle was just regular GM Synchromesh. It's a stupid question, but would combining the two fluids do any damage at all? After all, they're both Synchromesh, just one is more thicker.

I know I should return the one bottle, but I don't feel like doing all the shipping, etc.

 

You'll be fine.