My car was originally carb so the D15 is using same hardware as D13 i.e. Carburettor.
The colour of smoke I would say is bluish and smells of oil.. never had the water level drop in radiator in past 6 months other than occasional top up.. no mayonnaise in the oil cap either so not head gasket. We did take tappet cover off to check and its all clean..
for now I have had the chamber gasket replaced which is again leaking - i think the mechanic I went do didnt do a good job but other than that, only air filter and plugs have been changed and 1 oil change and almost 3 times I have refilled approx 2-3 liters of oil because its dripping so much from under the engine..