My recollection is that mineral spirits are recommended for thinning Pro-Custom Oil. I've used mineral spirits for thinning it to 'sand in' the first few coats, with good results. I too, have a couple cans of PCO around as well as a couple cans of the aerosol. The aerosol seems to be nearly clear, where the non-aerosol has a heavy red-brown cast to it that darkens the wood significantly.