How hot is too hot for winter grill cover?

I live in MI, the other morning I had 1/16" of ice on my car, today its 70.

I don't plan to put my winter grill cover on yet, but when I do, how hot is too hot to run it? I'm assuming its a pain to remove it and reinstall it. So, I want to wait till its needed... but I want to make sure that if we get a 40 degree in amoungst our 10 degree days it won't overheat?

Anyone have experience with this?

I have routinely run cardboard in front of my radiator at 50º F with no problems. The radiator fans never run in those conditions.

The covers aren't hard to put on... Once you understand how to install them. I am in Buffalo and have had mine on since I got them (the temp ranges from 35-70 right now). I have a short commute (when I DO drive) so I keep them on right now - today, for instance, it was 59 when I cruised in. I have not overheated.

We are headed to NYC in for Thanx. I imagine that I will take off the covers for any long distance trip (unless it is super cold).

The winter cover blocks about 40% of the air so it isn't an issue. Just put it on now while its nice out and its easy to do. Kind of like putting up gutter heaters for ice daming in Dec after it's snowed. No fun....

Cool, thanks guys... the UPS truck should be dropping it off shortly. I guess I'll throw it on this weekend.

I put mine on a week ago, temps ranging from 40F for a low to 70F or 75F for a high.

I use the closed cell foam pipe insulation to block the upper grill, lower grill, and I even block the insert in front of the intercooler when the highs are consistently lower than 30 F. I have never had a single issue in South Dakota; we experience the same temperature fluctuations.

A few other benefits:
1. This is dirt cheap (less than $5.00)
2. Once you have your pieces cut to fit this takes 30 seconds to install and less time to tear down if you ever encounter a temp issue.