need info on cluster buttons 1998 e320

[mespe]

The instrument cluster on my 1998 has 3 buttons on either side of the cluster. on the left it's 0 - + and on the left R M H I figure the M is minutes and H is hours, but I have no idea how to set the time. I do not have an owners manual.

I have seen a message pop up do you want to check the oil level? but I have no idea how to get that message, or what button to press to show the oil level,,,