I don't mean to be negative Nancy, but I am a little surprised this is being presented as something 'new' or 'revolutionary' (is it?) - people have said for a long time that putting coconut oil on tortoise shells is 'less harmful' than a lot of other stuff (e.g. mineral oil or that wax stuff). However, when people said it was Ok, the intent was certainly not to recommend daily use.
My tortoises have beautiful smooth shells, and I do NOT schmeer their shells with stuff. They spend April-October outdoors getting muddy, and they spend Dec-March in a fridge at 40 degrees, and the couple months in between, they have large tortoise tables with high quality lighting. I mist them several times daily, and I leave dirt on their shells. I don't think coconut oil would harm them. However, I don't find that it is necessary to achieve a healthy, beautiful tortoise shell. Beautiful shells are a reflection of a healthy lifestyle, so first and foremost, I think a tortoise keeper should spend energy (and money if necessary) on providing best possible food (widely varied dark leafy greens), ample space (preferably outdoors for part of the year at least), and high quality lighting and supplements.
Do your tortoises get to spend time outside?
One way in which you could expand their diet would be to plant some of the excellent broadleaf seed mixes that are available.
@TylerStewart has a great mix available here: http://www.tortoisesupply.com/TestudoMix
and Carolina Pet Supply has one, too: http://www.carolinapetsupply.com/catalog/index.php?main_page=index&cPath=41
This would allow you to expand their diet.
If you have yard space, you could build a fully enclosed dog-kennel type enclosure out of chain link fencing, with cemented in metal support structure. You could even add a lock, to keep humans out. Illinois gets very cold during the winter, but there are definitely some summer months that would allow for many hours of healthy outdoor sun.
Can you build a nice 6 foot tall private fence? Or even a six-foot tall chain-link? then you could build an enclosure with hardware cloth below and above to keep the critters out. you can also bring your tortoises and at night because that's when most of the bad critters are out anyway. Even just a couple months of daily outdoor environment and the natural sunlight will help. I live in Washington state and my tortoise is inside about six months out of the year. I feel bad about that but at least the other six months she has a great environment to be in. Definitely put some effort into more outdoor time for your tortoises when weather allows. My enclosure is then has a class that I can put a padlock through to keep people out if I wanted to. I Think a little bit of moderation would go a long ways in your experiment. Many many people here on this forum have indoor and outdoor enclosures. I do realize that there are situations were tortoises cannot be outside at all.and in these situations much more time money and effort has to be put into their care. I know it is the situation that you are exploring with The coconut oil.
I guess what I am trying to say is don't put all your eggs in one basket, don't expect the coconut oil to make up for the rest of the environment and care. I have read your coconut oil thread and I have started putting it on my tortoise every couple weeks. She is wild caught and has a very damaged shell. but I probably will not put it on in the summer when she is outside. I don't want anything coming between her and sunshine, rain, dirt etc.
I appreciate what you are trying to figure out. The problem is you don't have enough information to get a real answer. you will just be guessing not knowing. You can measure every minute from now till the cows come home and it won't matter, because you don't have a baseline control group. I hate to see so much enthusiasm and energy wasted.
The scientific method is there for a reason. Do you even know what it is? I think not. Not following it will not be helpful in anyway. you can ponder, toss around ideas, ask opinions, but you will not get an answer.not an accurate answer anyway.if you were fine with that then that is your right. but don't expect other people to give you any sort of in formed answer without all the facts.
It's been a very interesting thread and I appreciate what you're trying to do.
I was a bit worried about the temp of the tortoise. He always shows pretty darned hot.
Thanks for taking the time and trouble to do this and sharing it with us.