We have had several Italian restaurants in the area over the years that were family owned. One of the owners was kind enough to share her secret recipe for their Greek dressing back in the 80's in our hometown newspaper..I was lucky enough to see it and it has been a staple in my house ever since.
Mix all the above in glass bowl...stir with whisk. Now allow it to set covered for 8-24 hours..whisking every couple of hours for the first 8 hours. The longer you let it set the better the flavors will be. Do NOT refrigerate. Herbs want to settle at the bottom..so stir or shake before each use. Store in a glass container..bottle or bowl.
I did use a different cooking oil other than Mazola Corn oil..it made a huge difference..Mazola is the best for this recipe.