acrylic enamel reducer vs. urethane reducer

Looking on the TCP website the thinner listed under acrylic enamel auto paints is urethane reducer (see link below). New to this so question is is urethane reducer the same thing or a suitable substitute for acrylic enamel reducer? (I already have urethane reducer). I would of guessed no, but can't understand why they only list urethane reducer under their acrylic enamel associated products.

http://www.tcpglobal.com/restorationshop/rspacrylic.aspx

Anybody? Just trying to find out if i need to find a source for acrylic enamel reducer or if i can use the urethane reducer i have on hand. this is to paint my engine, not the body....

it has been a very long time since i used acrylic enamel so i don't know if i am accurate.
there used to be acrylic enamel reducer and urethane reducer, and there probably still is. the urethane reducer is has MUCH stronger solvents in it. when you use it over properly stripped and primed surfaces you shouldn't have any problems using urethane reducer. when you use it over older surfaces it may bite into the under coats and cause lifting.

p-sheet specifies that DT- series reducer can only be used when DU-5 is used and only in a 4:1:1 ratio.

DAR p-sheet