I haven’t heard of anything...but it’s a good idea.
My car had nasty water spots around the oil filler cap, and they proved nearly impossible to remove. The detail shop that did my PPF finally went after them and got most (but still not all) removed.
After that I put a towel under the engine compartment cover before I washed the car, which worked well...
...until I forgot the last time I washed it. BAM! Spots all over the oil tank again.
If you can remember the towel procedure — laying it out over the oil tank ahead of washing — it works pretty well. Also don’t forget to remove the towel after the wash (yup, forgot to do that more than once, but luckily it didn’t cause an issue for the short time it was there before I remembered).
It’s really only the oil tank area that’s a problem because it’s hot and the water instantly “bakes” onto the tank. Especially if you have hard water and/or lots of chemicals/calcium in it. The intake manifold, carbon fiber covers (“Powered By Ford”) and other areas can also form spots if you let the water dry on them, but they aren’t baked on by high heat, and easily wipe off later.
Definitely a crucial “tip” for anyone writing the “How to own a New Ford GT” guide.
