Lubricity tester.
https://diqn32j8nouaz.cloudfront.net...r_fullsize.jpg
Previously:
https://www.homemadetools.net/forum/...149#post161075
https://www.homemadetools.net/forum/...053#post168431
https://www.homemadetools.net/forum/...614#post159165
https://www.homemadetools.net/forum/...743#post159676
https://www.homemadetools.net/forum/...433#post158454
