I noticed after I spread it and when I water it in it smells like oil, not strong but defanlty a oily odor

It kills them after germination by inhibiting root development. Thus, it depletes the seed bank.

I'm assuming the HD pre-emergent is dithopyr, double check that by looking on the bag for the active ingredient. If so, you can use this label to determine what it's safe on:

http://tedcollinst-l.com/label/Dimension2EW.pdf

It depends on the active ingredient - some pre-emergents do prevent germination; others retard root development. And not all will be equally effective in the weeds that they will control. You need to identify what your problem plants/weeds are and use a pre-emergent that is registered for their specific control. Read the labels carefully.

Product Name:LESCO PRE-M 0.86% Crabgrass Pre-Emergent Plus Potash

- EPA Registration No.:10404-100

Synonyms:Dinitroaniline

Other means of identification:

N-(1-ethylpropyl)-3,4-dimethly-2,6-dinitrobenzenamine

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^^^ that stuff?