Hmmm...I put it back in the same way it came out I believe. The little plunger sticks out, right? The problem was happening well before I pulled the thermostat tho.

Was the engine mounted oil thermostat taken apart? I seem to recall the top flange is unsymmetrical so it only goes in one way? Jim

I was talking about the ext thermostat...

Get a hand help pyrometer.....it will tell you what the oil temp really is.....

http://forums.pelicanparts.com/uploads/gaugr221.jpg

Throwing money at parts is frustrating and a waste of time......gauges DO fail as do the senders. BTW, those numbers are in Centigrade.....

60=140F
90=194F
120=248F
150=302F

The top of the first thick white bar is 60 C or 140 F, the second bar is 90 C or 194 F, the third bar is 120 C or 248 F, and the red is 150 C or 302 F. That makes the 9 o'clock position of the guage about 105 C or 221 F. Is this how your reading your guage? If you are at or below the 9 o'clock position of the guage, your temp is good. With a fan on my oil cooler, I run about 210 on 90 F days and 220 on 100 F days.

Jim, I have heard that if air gets in the lines to the fender oil cooler, it can cause a problem getting a good quantity of oil through the cooler. I have not had the problem nor have I done any work on my external thermostat. I have heard on Rennlist that the thermostat can be installed wrong.

Well, I just ran to the store across town in about 65degree weather to find a thermometer...hit the 250f white bar. On the way home, hit a little bit of rain and she dropped to about 210-220 quickly.

Mikez, can I just put a thermometer in where the dip stick is and verify the temp there???

You can get a Raytek pyrometer(checks suface temp from feet away with lazer pointer) at NAPA for $85.
Also good to check if each exhaust header is running at the same temperature, if the radiator is blocked, AC plumbing is blocked(colder after the restriction), Cat is working(should be 100deg hotter after), and if your feet are as cold as they feel.

Matt, just a long shot and I didn't read most of the posts so this might have been mentioned. Anyway, if your car is equipped with a catalytic convertor you might want to check that it isn't plugged.

Wanted to try and verify at least ONE thing, so I set my sights on the ext tstat this morning and just removed it. Short drive on a cool 50 degree morning resulted in just over 200 degrees, and the internal cooler was hot (but not scalding) and the oil lines and front cooler were cold ??? Is my logic wrong about removing the tstat and it should full flow?

I'm going to get the temp verified in the next couple days when I can either get or borrow the pyrometer.

Will also check the cat. Should I try knocking on her and see if she rattles?