The posted coordinates will lead you to a petrol station, and we all know that lead has been sucked out of petrol sold in Singapore. How many diesel pumps are there at the station? Let this be H.
The holy grail of ancient alchemists is to turn LEAD (Pb, atomic no 82) into GOLD (Au, atomic no 79). Actually, there are a few ways to do it, but to get to our treasure chest, you have to do it in 7 specific steps.
The answers you get in the 7 steps will give you A to G.
Then use simple substitution to get the final coords:
N01° 17.[(C+D)/E][B-G+F][D-A]
E103° 49.[H-F] [D-C][(CxF)/D]
Lead not provided in the cache, so please BYOP.
You can check your answers for this puzzle on Geochecker.com.