Originally posted by Big Jim:
You really do want 5/30 in it but one time probably won't do any real damage. The weather up there is above freezing by now isn't it? If not, I would consider draining the 10/30.....
If we were getting temperatures below 20 degrees F I would change out. However our temp has ranged from 25 to 80 degrees F and back again over the past 14 days, so I think your safe.
For peace of mind you could always have them drain and refill, w/o new filter, for probably $10. if not less since they should have known the viscosity to use.