Mystery oil leak

[Jon48116]

I am new to the forum, and recently purchased a 1988 911 coupe. Previously I owned a 1976 930.

The '88 911 had a pre-purchase inspection that showed nothing of concern. Since then (4-5 weeks) I've driven the car almost every day with no problems and no evidence of anything leaking on the garage floor.

A few days ago I noticed a puddle near the right front (passenger side) wheel about 12 inches in diameter. It appears to be oil, definitely not brake fluid or A/C condensate. I've was unable to determine the source, but have driven the car for a few days since with not a drop leaking.

Tomorrow, I will put the car up so I can get a better look at things.

My question is, does anyone have any insight into how an oil leak can suddenly appear, then stop? Can the crimped oil line fittings do this? Any advise on where to start looking would be appreciated.

[Joe Bob]

Fenderwell oil cooler? Mine developed a leak from a bad weld on the bottem mount.

[Pazuzu]

Depending on where you live and how soft you've driven your new car, it's very possible that you have an oil leak somewhere near the front fender cooler, and that you've only once driven the car enough to heat the oil up high enough to open the thermostat. If the thermostat remains closed, then there's no pressure/flow through the fender cooler, and therefore no leak. Once you got it hot enough one day, the thermostat opened, oil flowed through the cooler, and you found your leak.

Or, your thermostat is wonky, and only opening rarely, even with getting the car warm enough.

[Discseven]

Good rationale Mike... I'll second it.

[Jon48116]

Thanks, Mike. That scenario makes sense.

We had some hot weather in Michigan during that time period, but the day it leaked and days it didn't were about the same in terms of driving time and ambient temp. I have no idea how long/hard the car must be driven to open the thermostat under those conditions, but your's is the best explanation so far.

I will make a post tomorrow after the car is examined.

Thanks again all.

Jon

[Jon48116]

Well, it wasn't oil after all, rather an A/C refrigerant.

[Discseven]

Originally Posted by Jon48116

Well, it wasn't oil after all, rather an A/C refrigerant.

How did you sort that out Jon?

[88911coupe]

I assume you mean ac compressor oil?

[GH85Carrera]

That is a really strange place for the AC system to leak oil. Can you find the source of the leak? There are no AC componets in the RF fender. The rubber hoses could have been punctured but that would be very unusual unless you ran over some road debris.