2000 4Runner, 42000miles, 5spd, SR5, 3.4L 3400 4Cam 24,new owners. Intermittent light smoke (smoke not vapor) at startup. Initial concern of ours and Toyota dealership was head gasket. Dealer did compression test and found to be okay. Dealer found leaky water pump, which we had replaced, also gear box service, timing belt, replaced spark plugs and oil change. Rig still blowing intermittent smoke at startup and after sitting a bit at restart. Coolant level holding. Found oil level to be very low after 1000 miles since oil change - no visible leaks. Concern about recent information we've found regarding sludge on other threads. Checked oil res cap and visual check of oil fill - thick black residue. (Comparing to my '97 Tacoma with same engine which looked clean) Looking for suggestions. Has anyone had experience with sludge/symptoms - is this a condition which can be remedied or do we bail now? Thanks for your help in advance.