Foxwell ST203 12V Car Smoke Leak Detector EVAP System Test Pipe leakage analyzer Car Diagnostic Tool. EVAP System Test. Foxwell ST203 Smoke Leak Detector Support Muilti System. Inject 10ml-20ml of test oil into the smoke leak detector, filling 20ML of test fluid, under standard working conditions, can be used continuously for about 10 minutes; (about Smoke Oil: advise use the Baby oil).