I think it is good to have premium chemicals in the ss bays. Self serve customers want and deserve the chance to have a high quality wash, just as if they were using and IBA or tunnel- the difference is that they don’t mind supplying the labor. Something like Simoniz Ceramic Sealant has a recommended final dilution rate of 256:1 in a ss bay. It is an expensive product, but customers can cover their car in about 30 seconds with it and then see immediate results with shine and water repellency- long term too. It does need to be rinsed, so you are getting some extra time out of the product but the real value is in the result that keeps customers coming back. I would say it is extremely important to advertise with the menu sign decals, dial decals and any other signage available - even outside the bays with banners, drum covers etc. Also, thoroughly instruct the customer that the car has to be very clean - presoak and/or brushed and thoroughly rinsed before the ceramic is applied and the ceramic must be thoroughly rinsed off as well. Not everyone will read the signs and follow the instructions properly - we all know that, but you can only do so much and you have to give the people who do read the tools to use the product properly for the best result. Many good brands out there. I only used the example of Simoniz because I use it and have good results. You will have a lot of choices that will probably work every bit as well.