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1988 Coupe Deville, 1991 Coupe Deville, 1989, 1994 Eldorado
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160 Posts
Discussion Starter #1
My 4.5 L engine requires a 195 degree thermostat
should I use a lower temp thermostat to keep the engine a little cooler?
thanks
 

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1995 Sedan De Ville (4.9 L)
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581 Posts
Yeah, I agree with adalla. If the engine requires 195 degree, which means someone spent a lot of time and money to figure out what the right temeprature is for that engine and everything should have been designed accordingly, I believe (well, I hope!). Well, at least, this is what I think...
 

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Cadillac Technician
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11,051 Posts
Lower T-stat temps will make your fuel mileage worse and your car may not perform the way you think it will.
Lower temp t-stats are okay for hot climates or the racetrack, but for everyday driving it's better to stick with what the car was designed for.
 

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1993 Eldo 4.9 66K miles
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368 Posts
jamesmdx1 said:
My 4.5 L engine requires a 195 degree thermostat
should I use a lower temp thermostat to keep the engine a little cooler?
thanks
No. The computer is looking for 195 to indicate the engine is up to operating temperature.
 

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Registered
1988 Coupe Deville, 1991 Coupe Deville, 1989, 1994 Eldorado
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160 Posts
Discussion Starter #6
Yes thats what I thought, I like to leave everything OEM, It just raised an eyebrow when I opened the hood on my 89 eldo and showed my engine to my friend and he said wow she's running a little hot... my temp display always reads out between 190-197. except when stop and go it might get up to 212-219.... which is normal.

I just think that the eldo doesn't have much room under the hood so it might retain some heat.

thanks - just wanted to see what everyone thought
 

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'87 SDV
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1,296 Posts
A lower temp thermostat won't make your engine run cooler anyway - you still have the same coolant capacity. All the T-stat does is keep the coolant in the rad from flowing into the engine, allowing the engine to warm up to normal operating temp quicker. When it hits 195, the T-stat opens and lets the coolant flow freely. The ECM brain reads that temp and adjusts fuel, timing and air flow accordingly. It's far more important to change your coolant every year or two, use the GM supplement tabs, and put in a fresh t-stat then. Stick with the factory's recommendation.
 

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1989 Sedan DeVille is now just a fond memory ....
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10,429 Posts
Back in the old days, using a cooler t-stat was a viable idea but now, with computer control it is a mistake to use a t-stat with a lower temp than OEM.
The best thing you can do is ensure that your cooling system is in top shape. No leaks, proper sealing radiator cap (proper psi rating), OEM t-stat that works (it's good to test them on your stove before installing, make sure they open and close when they are supposed to) and make sure you have clean 50/50 coolant mix with the GM suppliment tabs (or Barsleak equilvalent).
 
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