Ditto on the cardboard. I've been using that for years, regardless of the weather. Even just a single sheet makes it easy to slide around, and keeps you relatively clean and comfortable - especially if you are working in the driveway as opposed to a garage, which has been the case for me these past several years. My garage has, unfortunately, become a storage facility.

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1987 Mercedes 300D ~200K (Greasecar & Biodiesel)
1993 Ford F-250 7.3 IDI diesel 165K (Biodiesel)
1996 Thomas/International Bus with DT466 engine