They definitely make a huge difference, I experienced the same thing myself last year. This year I intend to do it myself for the first time. Hopefully I'll get the time to do so within a month, if not then I'll just have to pay the mechanic to do it.

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1999 Mercedes-Benz S600, 103K miles - garage queen
1988 Mercedes-Benz 560SEL, 89K miles - daily driver
2007 Hyundai Sonata Limited, 31K - daily driver