Was doing routine maint (new belts, O2 sensor, valves, fuel hose, etc.) and I noticed a clean drop of oil (like 90wgt) about to drop off the compressor housing. I also remembered that the last few times I used the A/C that the compressor was noisy and rumbling and sure enough it is. Is this thing toast or does it need service? It still blows cold, but there is alot of bubbling going on receiver/dryer window.