Some months ago I purchased a sump heater from you. I can tell you its fantastic. I live in Western Australia in the wheat belt where in winter the temp drops only to -3 but the oil in my engine is nice & warm, The engine heats to op temp so much faster now saving me lots of $$$$ on petrol i.e. running a rich mixture to op temp. The EFI unit only puts in the fuel required so the faster warm-up the more fuel I save. Great product & thanks a lot...