Oil Level/Leak Issues

[der Mond]

I'm daily driving my '87 Carrera (124K miles) in Alaska, and notice that my oil level guage starts registering when the temp needle moves a bit above the lowest shaded area on the temp guage. I have also been checking it at the dipstick like that. Today I followed a suggestion to blanket the grille and let it warm up good at idle, and despite the outside temp of +25 F., the fender oil cooler heated up just before the needle reached halfway up. At that temp the dipstick reading was about 1/4 - 3/8 inch higher than the previous reading. Does that seem normal? I would have expected more variance with the oil cooler and lines open. I was wondering primarily because I have developed oil leaks at both my lines between the external thermostat and the oil tank and engine oil line, and also what appears to be the front seal. I'd been thinking that if I was overfilling the oil, perhaps the oil that looks like it's coming from the front seal (and making quite a mess of the engine and tranny underneath) might have been from the "breather(s)" I've read about in other oil leak posts but haven't discovered yet, which other owners have said can make a mess of the engine if the oil is overfilled. But it appears that I have not been overfilling the oil, because I never fill it more than halfway between the marks on the dipstick. At the PPI at 118K miles, I was told there was a slight ooze from the front seal but not to worry about it until it was time to replace the clutch. Also, slight oozes were noted from the oil lines mentioned, but I was told it was better to not mess with those connectors until there was actual need, particularly the connectors at the thermostat end, because that could lead to additional problems. What do I need to know about replacing those lines? I switched from Mobil 1 15W-50 to Mobil 1 0W-40 in October to ease cold startup. Could the accelerated leaks be simply from the decreased viscosity? Could I have damaged the front seal further by starting the engine cold (-15 F.)? I have noticed that once it got cold outside, after the engine caught initially, about 1-2 seconds later there was another little soft thunk from the engine compartment - is that the sound of the oil encountering resistance? I also noticed today that on the lower oil line I mentioned, I could rotate the rubber portion back and forth a couple millimeters at the connectors with the engine dead, but not once it started. Is it adviseable to try tightening the connector fittings on these lines to try and stop leaks, or should I just replace them? I have no record to document if they were replaced previously. The engine leaks at about the rate of a drop every 5 minutes with the engine running. Should I just have the seal replaced? How expensive are we talking? OK - enough questions.. Thank you.