It sounds like there may be a problem to fully releasing the clutch if you are having a problem getting into first or second. First I would check the clutch fluid reservoir (takes brake fluid). You may have an issue with the clutch master or slave cylinder or just air in the clutch hydraulics, which makes it much harder to fully release the clutch to disengage from the flywheel.
If that's not the issue, then someone may have put too heavy a fluid in there that is making it hard to shift when cold. But when you are sitting still at a light, even in cold weather, you should be able to push in the clutch and within a second, just slide easily into first gear. If it tries to grind in this condition, you have a clutch release issue that needs addressed, not something that a different fluid will fix.