Stylemobile

Upon changing the first run of synthetic blend oil, I found a thick, yellowish sludge under my filler cap and around the threads at the top of the center rod that the capture nut grips. The accumulation totaled about two tablespoons in volume. It looks like mustard. (No, i did not eat any food while changing my oil.) Is this a precipitate from the synthetic blend oil? I cleaned most of it out and changed the oil using the synth blend again.

I will supply pics and more data upon request.

This is starting off as a simple question just in case there is a simple answer.

Allen in Allentown, PA

Dave H.

best case: condensation building up in the crankcase from short driving trips.

worst case: coolant in your oil.

oz928s4

You would think a milkshake was on the way...I agree coolant getting into oil somewhere...suspect headgasket maybe just starting to go...maybe intake gasket.

Shark Attack

its usually cream color. But this is normal if you drive short trips. The first time I saw it I freaked out. The engine oil filler neck is at the very top of the engine. Steam rises, thus this is where it collects.... Yellow color has me thinking though. Are you sure its yellow.

Jim bailey - 928 International

Normal condensation my wife's 79 would do that all the time . She only drove 4 miles to work most of the time and the car never got hot enough.

Mrmerlin

you can get a test kit for exhaust gases in the coolant.
Otherwise if the coolant tank is free of oil and the level is staying the same then you probably dont have any coolant leaks.
As stated your drive times need to increase to evaporate the H2O from the oil

Jim bailey - 928 International

Right take it out for nice long hard drives Both you and the car will enjoy it !

Leslie 928 S2

Uh....Allen...just this one time, please don't take Jim's usually accurate and fun-inducing advice, and please don't take your car for any hard drives until you get it here this weekend for Kevin to change those fuel lines and check your timing belt and tensioner.

Jim, really, really sorry to veto you on this one, but we got a first hand look at Allen's fuel lines at the drive we hosted recently, and....well...let's just say they look orignal. 'Nuff said.

Allen, hopefully Kev will be able to diagnose for sure what your mustard coolant is, too, when you visit. You will have a nice long couple of hour drive to get here, so if that is the problem, your mustard may have cleared up by the time you arrive. If not, the source of the problem may be more apparent after the drive.

Uhhh...I guess that's assuming you make it here.










Just kidding, of course!

tailpipe

Isn't there a hot coolant tube going through the breather hose from the oil fill/strainer to the aircleaner? is that tube there to keep the yellow crud from bulding up in that tube maybe check to see if that tube is still doing its job ?

paul with 4 79 928s

Vilhuer

Its there to keep breather from frozing shut in sub zero celsius conditions.

tailpipe

Sounds good to me Vilhuer it looked important to me three of the cars I have came with that hose removed and pluged but I had enough parts around to put them back right wasn't sure of its actual purpose thanks

paul with 4 79 928s

Vilhuer

In certain weather little below zero celsius breather can freeze very quickly in short drives where engine doesn't get hot enough to melt the ice. In most cars result is that one of the crank seals will blow out. Usually its enough for breather hose to have some isolation around it. In some cases problem is so bad that there are electric heaters installed in production line in certain car models to prevent this. Lot depents on breather location and inside diameter. In early 928 case factory thought its enough to run coolant through breather hose.

erwalker

Two points to make re moisture in oil systems:
1) Recently a young lady in our office bought a Mazda RX8. Looked at the oil level and the stick was covered in creamy froth - told her to call the dealer and get it back to their shop immediately. She was told by the dealer that the motor in her car is well known for accumulations of condensation causing this condition. Solution as given by the dealer - driver the hell out of it to boil out the moisture. I checked some RX8 forums and confirmed that this is a common issue.
2) I had a '94 Saturn that had a PCV valve that would freeze up when temperatures got very cold (i.e.-30 C) - valve cover gasket would blow out dumping hot oil all over the exhaust manifold. You could actually see small flames from the burning oil on the manifold! Some foam pipe insulation zip-tied to the PCV valve and hose cured that but it was an eye opener all the same.
"Curdled milk" appearance in the oil isn't always head gasket, but check for it all the same - better safe than sorry.

Stylemobile

Here are two pics snapped with the phone camera... color on my computer screen looks pretty accurate. I guess it's more green than yellow. Don't paint your car this color.....
This oil (Valvoline Synth blend) had been run for close to 5K miles put on in 3-4 months. Upon draining, you could see through the oil nicely as it exited the pan drain. The manager at my garage commented that the oil looked clean. Sidebar: I am good friends with the manager of a local shop and he lets me use the lift and work on my own car. I know some of you might be a little envious of this. No crawling under for me. No Sir. i get to stand straight up. Anyway, the driving is mixed use city, rural and highway. If this condensate has the ability to collect, woud hard driving after it collects make it 're-absorb' or is the accumulation going to stay? If it stays put, this is actually a great coincidence as who really wants stuff like this circulating through their engine? Removal was easy with a rag and some brake cleaner. I replaced with the same brand and type. Hmmmnnn.............

Thanks all for this great input so far.

Leslie and Kevin,
I had Roger drop ship the parts for my car to your home. They should be there Friday but had shipped to you just in case of a Saturday delivery. I would rather be on the road than waiting for my mail carrier. I will bring your front Bilsteins along as well. I am SO looking forward to hanging out with you two and playing with the car. If Kevin needs a 2nd pair of hands to help on anything of yours, keep me in mind for Saturday. ...and I promise to try to not blow anything up on the car before I get there.

Allen

Stylemobile

Addendum:
I have no coolant loss at all.
The coolant appears quite clean.
The oil itself has been/was quite clean.

But this color sure looks like coolant color, eh?
It behaved like cooled bacon grease under the lid and the stuff on the threaded rod was more like mustard. I drove the car gently for two miles to get the oil changed. The car was cool to start the trip and the ambient air temperature was around 55-60F. The weather was raining.