Hey i have a 94 X and i decided to flush the radiator out and put new fluid in. I drained the fluid and flushed it out with a hose and added some stop leak then filled it back up with 50/50 fluid and water after letting it idle for 15 mins with just water. Before i drained it my truck would show that it was running much cooler then it is not, and it would take alot longer to warm up. Now my temp gauge hits the N on the normal only after like 10 mins on a cold start, and sometimes it will be in the middle of the normal which it never ran that hotr before. Im wondering if the mixture is wrong or something and it would cause it to be running weird. I also changed my oil recently and used 10w 40 instead of 5W 30 on accident but it was running fine before so i do not know wats wrong.....the gauge is also bouncing around alot and when im idling it will show that its running hotter then when im driving. Please help outs guys i dont want to blow my truck up.

pretty much all engines will run hotter while standing still because there is less airflow through the radiator. As long as the gauge isnt going up and beyond the normal range, i wouldnt worry about it too much.

but i want to figure out why its different now, and why the gauge is moving around. ANd do you think im cool with running 10w40 or should i change to 5w30???????
Thanks alot.

I woudl think 10w40 would help cool your engine more because it is heavier. But I dont think you have to worry about anything unless it goes above normal.

I would think that it will take more power (read that as heat generated) to pump and overcome the increased viscosity of the 10W40 as compared to the 5W30. I would suspect the radiator stopleak is causing more of a temperature rise since it is coating the inside of your radiator passages and preventing good heat transfer to the fins from the fluid passages.

Unless you have compression problems, I'd stick with the 5W30. I have 196,000 miles on my '94 and still use 5W30 Mobil 1. I don't use any oil between changes at 6K miles.

I always run 10-40 in my '91.

The gauge: It's odd that it changed from what it was reading before you did the Flush. It would bothert me too. My 'X' has done what you are describing since I bought it. It seems to always run at the 'N' but then sometimes will drop to cold. At an idle it may creep up past 'N' but that is 'normal' in most cars. I don't think you have any problems but you may have shaken something up. and it logged someplace it shouldn't be.
Was the previous antifreeze mixed the same?

Sounds to me like you have air in the system.
Purge it out.
Have you ever replaced the thermostat or did you just recently?