What does your perimeter look like...how much of China do you have? Given that you are losing 5k resources a day, you can't be at the extent of your Empire especially if lots of it are at Nauru Island.
You should be plus 10-15K in resources a day, maybe more.
Generally speaking repair oil if you can keep it for longer than 90 days.
To answer your question, you can save 5K to 20K a day, depending upon factory (plane, r&D, engine, oil) repairs. Reinforcements, replacements, bombing, etc. all eat up supply. Drawing planes from the pools really eats supply fast, as does rebuilding an infantry division or twenty.
Depending upon the scenario you want to go into 44 with 3-6 million. I think in a scenario 2 game it is possible to go into 45 with 8 million -- but that really requires a deep understanding of supply usage and keeping the Allies at bay. I have seen good players hit 45 with less than 2 million, and if the Empire is intact and still producing supplies that is not too terrible either. But to hit the endgame with 2 million in supply and the HI under air attack makes life really difficult.
A lot of it depends upon where in the third generation plane builds you are as that will eat up 1 million in supply easily.
So your 1.7 million supply can be good or bad, depending upon how much you have already spent enlarging engine, plane and r&d factories.
You need to most likely prioritize fixing the oil centers; try to save on average 200,000 supply per month, and if you hit that goal, try to save more.
Spoilage can be checked in Tracker: resources, sort on spoilage column. I bet you have some, but probably fuel.
Your vehicle pools are very low, your vehicle production is on the low end of acceptable. Come June of 1944 you will struggle to get those great new tanks into your formations. I would suggest you start to save points now by stockpiling motorized support and being very careful which units you allow to get them.