GSF are often mentioned here. This is a warning to people to double check that the items they provide for a particular purpose really are suitable.
I bought some transmission oil from them after an email to them to double check that it was suitable. When it arrived, I emailed the manufacturer and was told that it was not the correct product. GSF did not stock their recommended fully synthetic transmission oil.
I also bought some power steering fluid. I entered the make and model of my car to access the fluids - and again on the online order form. Once again I emailed the manufacturer of the item supplied and was again told that it was not the correct product.
I'm glad I double checked.
To their credit GSF they did arrange collection and refund.