This vs So

Not sure I've ever seen the rule about never using "this". For instance, there is nothing wrong with the following sentence about maintaining proper air pressure in your car's tires:

I don't think it's a rule, just a stylistic preference. I wondered if using it was like using "get"--frowned upon. Guess not. Thank you for your input.

I don't think starting a sentence with "this" is bad at all. But there is a reason why you have been told that, I suppose. You always need to be mindful that "this" may not have a clear referent, and, if not, use something else.

It's often quite clear from the context what "this" refers to. At times, you may want to use "this" as a summary of several sentences without repeating them all. Or "all this," or "such considerations," "these things," etc.

Thanks to both of y'all.

Peren, I've als=ways used both liberally, but usu with ref to the foregoing sentence