I'm QF gold, thinking about booking Jet Airways flight (9W coded for the entire journey) from Sydney to Delhi/Mumbai via Singapore.

I'm QF gold, thinking about booking Jet Airways flight (9W coded for the entire journey) from Sydney to Delhi/Mumbai via Singapore. Would I get lounge access for Qantas operated segments (Syd<-->Singapore), although they are not QF coded? And what about Jet Airways operated segments?

To put it simply, my question is do I get QF lounge access for travelling on non QF coded but QF operated flights? 
Thanks in advance. 

No lounge access. You need to travel on a Qantas or Jetstar flight number for access. 

I flew 9W BNE>>>SIN in January (in business class). Boarding pass printed out with th QF flight number on it together with MY Lifetime Gold status. I will be surprised if it is a probelm for you.    BUT   Be aware, the points (going on to QFF) were a total Ba...sup for both me and my brother and took a few months to sort out. Most important to hold on to your boarding passes.

1) The nature of Asubsk's question, implies that he/she will be flying in Economy since access to the Business lounge on the basis of one's FF status is irrelavant if one flies in the Business cabin.

2) Given that Asubsk did not specify the type of lounge (First or Business), we can further imply from the question that he/she was referring to the Business Lounge as reference to FF Gold status was made. Access to the First lounge is available only to FF Plat status or thoes flying in the First Class cabin.

3) Since 9W does not operate a First Class cabin on the SIN/BOM sector nor does QF on the SYD/SIN sector, and given the substance of no. 1, above it is safe to conclude that travel will be in Economy.

Having said all that, given that there can be manual override of the system through poor application of the lounge access rules by the lounge agent, you can definitely try to access the lounge. Success depends on how well the lounge agent knows the rule and how willing they are to let you through when "the computer says no".

@readosunnycoast - I hope they print the QF number in my boarding pass for upcoming Mel-Sin (9w J)- have OW emerald and if that happens will be able to head into QF F lounge.