I was cleaning a school a couple of weeks ago and the windows at the front (south facing) had a really baked on crud all over the frames. My sprayer of Virosol ran dry and needed filling. I went back to the van, grabbed a container and mixed up a fresh batch.
It was only when that one ran dry that I realised that I hadn't used Virosol, but a safety floor cleaned that was the same colour and was also orangey.
It worked just as well as the virolol and I would say that just about any similar detergent would do the job.