I have a few questions. First of all, will it make my car start easier in the winter (less cranking?). Where can I get this car. And can I just change out the relay without changing plugs (without creating a compatability issue). I'd like to wait till it's a bit warmer outsided to change the GPs, as I don't have a garage, and it's been below freezing here for about a week. Thanks guys!

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1989 300E 144K

It won't make it easier to start, but it will certainly help it run smooth after the start and with less smoke. You don't need to change the glow plugs right away, just the relay. Just change the glow plugs when they fail on a case by case basis.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL