I put in a block heater onto my 1989 420 SEL last year. I remember that it was made in Winnipeg Manitoba, but the brand name escapes me. When installing it, be sure to have some of that high temperature high pressure petroleum product safe pipe thread leak stopper. I bought mine at home depot. The teflon tape did not work for me, after 2 tries.

I use mine when the temp goes below -10c, only for 2 hours prior to starting. It certainly helps to warm the block, especially the coolant and oil.

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1989 420 SEL