A drilling fluid including at least about 2 wt % olefin, at least about 5 wt % n-paraffins, and at least about 2 wt % isoparaffins, wherein the isoparaffins are substantially wholly terminal monomethyl branched is provided. A well set on the optical axis is illuminated through transmitted illumination provided by a transmitted illumination device. The timer allocation can include equal or weighted percentages related to the plurality of RATs, and a timer can be split according to the percentages to attempt connection using a RAT during a corresponding portion of the timer. The mantle surface is equipped with two recessed parts which run peripherally around the mantle surface. A plunger assembly defines a solenoid channel in which a solenoid can be received.