Expert: Sean Halliday - 3/18/2008

Question
I have notices that under my oil cap is a yellow thick substance,  nothing shows up in dipstick, tough,  also is strange whistling sounds that occur over 20 mph with or without pressing acclerator,  just had high mileage oil change done,  almost 124,oo0 miles,  just had tranmission done last year

Answer
High mileage cars will have this in the cap possibly because of worn rings,valves.It is caused by condensation in the crankcase.Or lack of regular oil changes.You may need to change the pcv valve and check the crankcase breather is not blocked.As for your whistling sound,i cannot tell unless i hear it.You need to pinpoint where it comes from.You dont say what make of car you have.