Normal Operating Temp
Howdy. I registered here to pick your brains about my truck. It's a 2001 Ram 1500 that I bought new in 2000. The other day the outside temperature was 100 degrees and I was sitting in traffic and I noticed the temp gauge was past 210 and rising. This was very hot for my truck, normally the gauge runs about 1 or 2 widths of the needle past the bottom line of 'normal' range (winter it's 1 width, in the summer it's 2). I'll attach a picture if I can figure out how.
I also noticed that the oil pressure was lower than usual, but both readings were still inside the brackets. I cranked up the heat and the temp leveled out. Then when I got moving again the oil pressure went back up and the temp dropped below 210 but was still way higher than usual. By now the sun had set so it was cooling off outside. When I got stopped and checked it out, the only thing I found wrong was that the radiator needed about 3 cups of water (the truck was not hot, I stopped and had dinner). The reservoir was full though, so I'm wondering why it didn't suck it from there. The cap was also on too tight. Whoever had it off last must have been a gorilla. I'm a big ole boy and I couldn't get it back on like how I found it.
I took it to my mechanic the next day. He said he found a fin that was bent that directs air to the radiator, but that's it and he thinks this is where the temp is supposed to be. I've got a stock 195 thermostat in it and always have had. Where you see the gauge in the picture is where it's been running for 520k miles. Somewhere I have a pic of the odometer when it got to 1k miles, if I find it I'll post it too. Right now, the needle is halfway between that lower bracket and 210. That's probably only a 10 - 20 degree shift, but it aint right.
Oh and for the record, 100 degrees may be the hottest day we've had this summer, but this truck has been in Texas all it's life. It's seen more days over 100 degrees than it's seen under 50.
Also of note, that check engine light you see in the picture is actually the computer complaining that the engine wasn't getting to temperature fast enough. BUT, that light was relatively new when the pic was taken. About a month ago I had the thermostat replaced and it was running at the same temp until last week.
So my specific questions,
1. Where do your temperature gauges run? My search of the itnerwebs tells me that my truck must be an outlier of some sort.
2. If I am an outlier, why would I be running so much cooler? Could my gauge be out of calibration?
3. Any thoughts on what could suddenly be making my truck run hotter? I have a very good mechanic, but he was busy and didn't look very hard this time because he thought the temp was right where it was supposed to be.
4. Last time I changed the oil I accidentally put in 5w-30 instead of 10w-30. Could that be causing the issue? I use mobile 1 full synthetic high mileage.
Thanks for your time.