My 83 diesel I4 has 3 core plugs, one of which I've replaced with a 120v block heater for use in cold temps, and which helps immensely.

A friend with a waterboxer Vanagon (not sure if it's a 1.9 or 2.1L) asked if one could be installed in his engine but I don't know if these engines have core plugs. A bit of online shopping turned up nothing but inline coolant heaters which are installed waaay up near the radiator, and hot-plate-style contact heaters which must be somehow adhered to the underside of the oil pan.

Anyone know of a simpler, more effective solution?

Jeff