Ok so today I replaced the diff fluid. I remembered the 140 but after I replaced it, I realized that I should have put 75/140 not 85/140. Is this going to be a problem? Should I replace the 85/140 out. I put in a synthetic blend that says its ok for limited slip. Drove around the block and dont hear any noise or anything. Thanks

 

Is the gear oil you used API GL-5?
The weight itself won't be a problem, but it needs to have the proper API rating.

 

API GL-5 MT-1

Its not going to be cold here for a while. Looking at over 120 degree days soon.

 

At lower temperatures it will be slightly less viscous, when it gets REALLY COLD (like the -40 I used to see in the mountains in Colorado) it is better to be less viscous as the oil will flow - but a 75 doesn't flow well in these extreme temps any better than the slightly heavier 85. When up to operating temp it will have the same ability to perform because they both only thin out as much as a normal 140 weight oil - no difference there.