What would cause a milky brown buildup on my dipstick and oil filler cap besides water? I checked my oil today and noticed the buildup, so I drained the oil and there was no sign of oil mixed in. I recently had an issue with my heater core so my first inclination was that I had a blown head gasket. I drained the oil and there was no sign of water mixed in. WTF?

 

Short runs & colder weather (or an incorrect thermostat), will cause a condensation build up in the crankcase, & give the symptoms you have.

If that is the cause, taking the truck for a long hot run will fix it, evaporating the condensation out of the crankcase (& valve covers, oil filler cap etc).

 

Yes, and also make sure your PCV system is working. A quick way to check is while the engine is running, pull the PCV valve out and stick your finger over the end of it. If it sucks on your finger, you should be ok on that point. It's what sucks all that junk out of the engine when you get it hot.

 

I completely agree with Ken, and Dave for that matter. But the right thermostat for your truck, and I don't even know what engine it has, is a 192 or 195 degree unit. So if you have a colder stat and do the long drive Ken suggested you will be right back here after a few short drives until you put the right stat in.