Been doing some normal maintenance for the last few days on my 39 convertible. Coolant has been in for a number of years and looked a little nasty looking in the neck. Drained it and it was't bad looking, the crud I saw was like the ring in a bath tub, it was floating on the top. I rinsed it and put some 20 Mule team cleaner, some Arm and Hammer heavy duty cleaner and some liquid oxiClean (this is what was laying around) and ran it about 1/2 hour, drained and flushed GOOD. I put in 2 gallons of Preston permanent anti freeze, 2 bottles of Water Wetter (couldn't find Purple Ice so I thought Id try WW) and a large bottle of Barrs heavy duty aluminum stop leak. This was in the afternoon yesterday when it was 95 degrees and let it run about 30 minutes and it got up to 190 when I shut it down to leave it sit over night. With a 4 lb pressure cap the pressure in the system sitting over night will push the Barrs into any small leak that may be in the block, heads or gaskets sealing them. This morning I did a few more things and at lunch time I took it for a ride it was 95 out, the coolant temperature was 175 when I stopped for lunch. Came out and drove 7 or 8 miles to Home Depot and it was up to 175 again when I went in the store. Came out in 15 minutes and the coolant was 190 it took about 8 turns of the engine to fire it, it usually starts as soon as I touch the starter on the first turn so I guess the high temperature boiled the gas out being so hot. Drove about 1,000 yards and it was back down to 175. The only cooling modification on this car is Skips pumps and the radiator was recored 30 years ago. No thermostats. It also has one of his coils. It gets a little warm working down here when it's this hot, it is even warmer in the shop with no air conditioning then it is outside, I drink lots of water. G.M.