Almost any non-drying fluid will serve as a honing fluid, although on smooth-ish stones (some natural stones for example) a lubricant is a positive disadvantage. The function of a lubricant is to separate two surfaces, the opposite of what you want when abrading.

I've briefly tried all of these on a fine Aloxite oilstone. (But recently moved over to a diamond plate).

Traditional

Neatsfoot oil, I used it for many years.

Usually recommended by stone suppliers

Cycle oil or "3 in 1" oil

The universal magic fluid?

WD 40

Kind to the hands?

Washing-up liquid

Avoid sump oil?

Thinned down engine oil

The medicinal stuff

Liquid paraffin

Pricey

Redex petrol additive

Ditto, but nice aroma?

Baby lotion

According to some people

Water

If it is old, it must be good, mustn't it?

Glycerine thinned with methylated spirit (3 to 1). Recipe gleaned from a nineteenth century book.

Reputed health risks?

Brake fluid. I've been using it for several years now without any evident ill-effects, but my exposure is not very great.

Hints on Oilstones in Cassell's Cyclopaedia of Mechanics, Volume II, (ca. 1900?)

Sperm, olive and sweet oils are given as serviceable.

Ditto

Soap has been recommended for the purpose [of facilitating honing]. The stone is wetted and rubbed with soap and more water is applied until a lather forms. This is allowed to dry, and when the stone is required for use it is merely necessary to wet it slightly. ..."

Conclusion?

Almost any fluid you can think of that is non-drying, not too viscous. It should be able to float away the metal particles and thus prevent them being embedded in the surface of the stone.

I suspect that some of the special honing oils sold to woodworkers in small quantities/high price are engineer's honing fluids intended to be used in copious quantities on precision grinding machines.

Do not use

Linseed oil. It is a drying oil and will form a skin.