I agree with Scott Tucker to a point. I wouldn't say you should 'never' use RTV on a cooling system gasket, as I've done it more times that I could count.
But I WILL agree that it isn't ideal. Silicon RTV is quite slippery before curing, and I've seen it cause gaskets to distort and slip out plenty of times. And it doesn't hold up that well to antifreeze- it's often soft and coming apart when I remove old cooling system components that were installed with RTV. Personally I prefer something like Permatex high-tack, permatex #2, or even anaerobic sealant in such applications. RTV can work ok- but you DO have to be more careful about overtorquing.
But one thing to consider is that silicon RTV is the go-to gasket-goop for all inexperienced techs... simply because it's the most common. So when I see shoddy work (often of the shade-tree variety), it's often slathered with a generous coating of RTV. Doesn't necessarily mean that RTV is a 'bad' sealant- but it IS the sealant preferred by 'bad' mechanics.
But I WILL agree that it isn't ideal. Silicon RTV is quite slippery before curing, and I've seen it cause gaskets to distort and slip out plenty of times. And it doesn't hold up that well to antifreeze- it's often soft and coming apart when I remove old cooling system components that were installed with RTV. Personally I prefer something like Permatex high-tack, permatex #2, or even anaerobic sealant in such applications. RTV can work ok- but you DO have to be more careful about overtorquing.
But one thing to consider is that silicon RTV is the go-to gasket-goop for all inexperienced techs... simply because it's the most common. So when I see shoddy work (often of the shade-tree variety), it's often slathered with a generous coating of RTV. Doesn't necessarily mean that RTV is a 'bad' sealant- but it IS the sealant preferred by 'bad' mechanics.