Varsol, AKA Stoddard solvent.
It isn't very flammable. I've seen an angle grinder discharging sparks directly into a parts washer with it in it and nothing happened.
I used to clean parts in it for hours some days, with no gloves. I had no adverse effects. However I seem to have been sensitized to it over the years, so now even brief exposure gets my skin broken and burning, so use gloves no matter what you use. It's not odorless by any means, but is surely light years ahead of diesel, aka, the stench that will not die.
Super clean will take your skin off. It has sodium hydroxide in it, which is lye and sodium metasilicate, which is also corrosive. We have a 208l drum at work, and under the tap used to dispense it, it has dried out into a white crust. It has dried out and split the polypropylene drum dolly it is held in. Nasty stuff at full strength. It will likely destroy any rubber seals and hoses in short order.