Shower tile ?

It's probably hard water/soap scum build-up. Fill a spray bottle with a 50/50 solution of Dawn dish soap and vinegar. Spray it on the tile and let it work. Use a plastic scrubber to remove any leftover build-up.

I use 5-6 oz of blue dawn dish soap with 20 oz white vinegar, mix it up and spray onto your tile, let it hang out there are 15 min, then scrub off, rinse well.

no do not use any type of oil on shower tiles - here is info on getting them to shine

https://homeguides.sfgate.com/restore-shine-shower-tile-93818.html

This is what I use to clean my entire bathroom. It works great on showers, grout, tile and potty. Heat up 1 cup of white vinegar, mix in about 1/4 cup of Dawn Premium. Not the dollar store kind, because it is too thin. When mixed, pour into a spray bottle and fill with water. Shake. Spray down the grout and let it sit overnight. In the morning rinse. If you have stubborn stains, spray again. Use this mixture a few times a week. It will keep your grout and tiles clean. Also works wonders in the toilet bowl to keep hard water stains at bay. Oh you only have to heat the vinegar one time when you add the Dawn.

Yes, you can

I've read that car wax like Turtle Wax is supposed to be a temporary fix to shine up tiles and shower doors... just be careful not to was the shower floor, it would make it slippery.

Check theses out

https://www.hometalk.com/diy/clean/bathroom/cleaning-shower-tile-amp-grout-what-works-and-what-doesn-t-669909

https://www.hometalk.com/diy/clean/bathroom/how-to-clean-natural-shower-tile-the-right-way-marble-granite-glass-27690767

Yeah - I'd try lemon oil! If what's making the tiles dull is built up soap scum, the lemon oil will help!

I use a steamer first to remove all the ick that has settled on the tile and then I clean it with warm water and vinegar. Works great.

Hi Linda, here's some info that may help.

https://www.hunker.com/12002304/how-to-polish-bathroom-tiles

Oil wouldn't last long and could be a fall risk. They make a product called Gel Gloss who have polishers and cleaners. https://www.google.com/search?client=opera&q=polishing+shower+walls&sourceid=opera&ie=UTF-8&oe=UTF-8 You can also use auto carnuba wax to buff the shower, but do put down a shower mat so you don't suffer a fall when the surface gets wet and slippery.

Hello this link might be helpful

https://sawshub.com/how-to-make-tile-shine/

Thank you all very much for your valued information. With Appreciation Linda Peters

It is more then likely just got hard water on it. CLR will remove it and make it shine

Here is some tips on getting them to shine: https://www.youtube.com/watch?v=n_L_GaCHvNg

I swear by comet it works great on tile

No lemon oil ,you need to get the soap scum off Clorox cleanup and a scrub

Mix vinegar and blue dawn, 50/50, and heat in the microwave. Then saturate the tile and let sit. If you need to, you can scrub with a non abrasive scrubber. That should remove all the build up.

I would advise against any oil in the shower. It's messy and slippery.

You could check into a sealant that has a high gloss.

Unless you want to break your neck, I would not recommend any kind of "OIL". Perhaps the dull look is because there is a build up on the shower walls. If you have hard water, clean it with tub & toilet "Lime away" as that will remove the lime build up. Beyond that, mix up i baking soda and vinegar, then add Dawn dishwashing soap. Spray it on and leave it for about a half hour before rinsing off.

If none of that works, you may need to paint, and yes, there is a special paint made for tubs and showers. I think it is made by Rustoleum!

I would never use oil in a shower. Will end up on the floor of the shower and make it dangerously slippery. Try Awesome cleaner from the dollar store to clean all of the soap scum off of it rinse then buff with an old towel.