What is this gunk in my dry sump oil reservoir?

I keep finding slimy yellow stuff around the top of the oil reservoir in my dry sump 76 308 GTB (see attached photo). It doesn't appear to be in the actual oil but just collects around the cap and on the top inside of the reservoir. It looks like the old girl has a bad cold!

I think I read somewhere once that it the result of the car making lots of short trips and never warming up properly. Anyone else come across this? It seems to get worse in the winter months, but car runs fine otherwise.

P.S. No jokes please, we're all adults (I think!)
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It might just be condensation from a lot of short trips, but it looks like quite a bit to me. You may have coolant in your oil for an unknown but potentially expensive reason. I have an early dry sump glass car, and have never seen anything like that, although I live in a very dry climate (Colorado).

 

Thanks. This is also an early RHD glass dry sump car, but our climate (Melbourne, Australia) goes from stinking hot in summer to wet and cold in winter. As mentioned it has only started to appear again in the past few weeks as our weather has started cooling down. Car does not appear to be losing any coolant so I've pretty much ruled out coolant/oil contamination (I think)...

 

I would still get it checked out Ossie, give your mechanic a quick call. The weather of late has been quite mild and the humidity hasn't been that high. The combination of H2O and oil make the yellow gunk. Perhaps you just need to drive it a bit more.

 

Check your water reservoir and see if it has the same gunk.

 

Yes, I hate to say it --- but I agree --- it may be coolant contaminating the oil system.

However, unless you have owned that car since brand new, you can't be certain that someone didn't add some sort of "additive" to the oil along the way. Do a pressure test on the coolant system for leaks ---- if it's okay, change your oil, and see if the goo comes back (you may need to change the oil several times to get rid of all the residue).

 

Oh,oh,

:-/

Pull, rear head... Ill bet the gasket is failing or close too.. Then, pull the motor.
(ouch, Here we go,,, $$,$$$.$$ !!!!!!!!!)
I'll bet you can get in and out for like, $ 8,000.00

Good luck,
Love the car,, wanna trade now...?

Edwardo
1981 Mondial 8, Euro with CA papers, no cats ever.
Balanced and blueprinted 2V 308 motore'

 

Thanks guys, yes I suspect coolant is the most likely, although I've driven the car at least 4000+ miles in this condition in the past 12 months and it doesn't seem to be getting any worse or causing any other issues. A pressure test of the cooling system sounds like a good idea so might start with that and change the oil again as a precaution.

Doesn't concern me greatly if I have to pull the engine as I know it's down on compression on 2 cylinders anyway and I was expecting to do rebuild at some point (just need to finish building the new workshop first!). In the meantime just plan to continue driving and enjoying it as it still runs like clockwork.

 

Coolant (if it is) in the oil AND low compression in one or more cylinders is fairly indicative of a blown (or at least leaking) head gasket, mate.

BTW, when you do your pressure testing, do two separate tests --- one with a cold engine, and one with a hot engine --- it's important to do both for accurate testing.

 

Another vote for short trips. Check your crankcase breathers. I've seen really bad formations of gunk there.

 

This is totally normal behavior.

What you have there is a "foam" that is made up by a suspension of water in oil bubbles.

There will always be a bit of condensate water in the oil system. As the oil travels around etc. it can form a bit of foam. The bubbles in the foam will contain water vapor. The part of the oil system (the filler neck) is also the coldest part of the system so it is completely normal that you will find this gunk there as it is the first place where as the oil cools it will form a lower viscosity greasy concentrate.


The filler neck will not warm up enough to melt all the deposit on short runs and so you have a build up.

This usually forms more in lower quality olis (or slightly older higher quality oils). You can find additives to prevent it, or use oils (like Redline 10W-40) which have an anti foaming agent added to them.

I see it more in winter than summer.

So, I say, If she has a snotty nose, then wipe it for her? (trying to remain adult about this)

M

 

+1 , looks like condensation. Check out the easy stuff first and don't suspect a major issue. Do the cooling system pressure test and if you want to do something else then drain the oil and send out a sample for analysis.

 

Agreed, I've seen this on other dry sump cars (More prevalent with high paraffin content oils). Wipe it out. Pressure check the cooling system. If all is well, take it for a good LONG drive... at least 40-50 miles. When you get back, crack, don't open - just crack the oil cap and let any pressure bleed off then close it and let things cool down.

If you are just encountering condensation, a long drive will boil it out of your oil system and most will be driven off via the normal breathing of the crankcase. You may get a steam pocket in the dry sump tank so be sure to crack the cap just in case the normal venting is not working.

Rick

 

"Doesn't concern me greatly if I have to pull the engine as I know it's down on compression on 2 cylinders anyway"

Are they adjacent cylinders?

 

My girlfriends Toyota Tundra did this with the factory dino oil in the winter months (lot's of short trips). I changed it over to Mobil 1 and it stopped doing it immediately.

 

When the comprssion is down on 2, you have to be careful, very careful. Better test coolant pressure and do it the right way. Then again, if you have compression loss, it is time to do some serious maintenance. And if you have to adjust the valves, take of the heads too and replace the gaskets. It is easier/cheaper to do it all at once.

I'd say, pull the engine. Better safe than sorry. It the oil is contaminated with too much coolant the mains and crank will die!