lacquer thinner

If this helps Lacquer thinner in England is called cellulose thinner.  Now days most Automobiles are painted with Enamel, the stuff to thin it is called reducer.  Enamel reducer made by Dupont usually is composed of the same  chemical components as lacquer thinner but, not always.  To be on the safe side don't use enamel reducer as a general purpose thinner, you might end up with a glopy mess.

"Lacquer thinner" does not have a single, uniform composition. It is essentially a generic name for thinners intended for use with true lacquers, but may also work with various other coatings. Lacquer thinner may contain any or all of the following, and this is by no means a comprehensive list:

mineral spirits, naptha, toluene (toluol), xylene (xylol), methyl alcohol, acetone and/or other ketones, particularly methyl-ethyl ketone (MEK), carbitol, isopropyl alcohol, butyl alcohol, methylene chloride, etc. ad nauseam…

As most automotive coatings are called lacquers, it is possible that your "automotive thinner" is, indeed, some form of lacquer thinner.

If a coating's instructions say that it should be thinned with lacquer thinner, then anything sold by that name should work. 

by automotive thinner i mean the thinners used for car paint. in Australia it's called general purpose thinner.

You can get lacquer thinner at most home improvment stores, Home Depot, Lowes and Ace Hardware.  Some Auto Parts Stores and Walmart sell lacquer thinner.   I've never seen Automotive thinner.