Low Operating Temp on Engine Oil

[SteveD2]

Some modern computer controlled engines will see the lower coolant temperature as an engine that isn't fully warmed up yet and keep the fuel mixture extra rich. Your engine won't run as well, it'll burn a lot of gas, and it won't have clean combustion.

Stick with the original 190+° stat. Your engine runs better. If it overheats, find the real problem and fix it.

Ken

 

[Dominic]

I was simply curious about oil problems Ken, thanks for your advice but I do prefer my 160 stat.

When running down the interstate I find I can only get 27mpg with the stock 195 stat @ 90mph... swap out to the 160 and instantly get a consistant 32-33mpg @ the same speed... I know there was a big change in thermal efficiency

I have noticed no problems running a 160, and using the newly reprogrammed fans it stays between 170-190 most of the time - runs simply stellar. Around 195-230 I really get a huge loss of power at the drag strip, and once again my fuel economy goes to hell.

Thanks for the replies... keep them coming for those who have opinions not on the 160 stat but on running an engine cool and its effects on wear, oil dilution, and such. I'd like to see if anyone has any reports on this matter

 

[Drew99GT]

I used to have a 180 degree stat in my Grand Am, which came factory with a 195. I have no way of reprogramming the fans, so the lower temp stat did absolutely squat in the summer, still ran at 215 in stop and go. However, in the winter time, my milege was absolutely gone with the 180 degree stat. I was actually running around 170-175 with the heater on full blast (confermed with Tech 2). Also, it didn't run very good at all, and when I changed the oil on cold days, even with the car at temperature, the oil didn't even burn me. I recently switched back to a 195 degree stat. My milege, power, and smoothness are back, and when I changed my oil 3 weeks ago it was actually hot to the touch. I just changed my plugs also, they were absolutely blackened with carbon and crud, a sign of way too much fuel in the mixture. Stock temp thermostat is best IMHO, even for high performance. As long as intake temps are ambient, coolent temps of 215 -220 are still good for power if you aren't getting detonation. Heat = power

 

[monarch]

One thing we know for sure is that in the 50's and 60's before emmission controls were important, virtually every car - foreign and domestic - came from the factory with a 180 stat. So that's a hint that 180 is the ideal balance of power, economy and durability

 

[Patman]

I ran a colder thermostat in my 98 Formula, and in the summer it didn't hurt the gas mileage, but as soon as it got into the 50s and lower, the gas mileage took a huge hit with that cold thermo, as my running temp would barely go above 175F. Switching back to the stock thermo in cold weather brought my mileage back up to normal again. I would never run a colder thermostat in anything less than 60F again, there is simply no need anyways. Only in very hot weather is it a benefit (it will lower or eliminate power robbing spark retard on those engines such as mine which are higher compression and run a fairly agressive spark curve)

 

[Drew99GT]

quote:

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Originally posted by monarch:
One thing we know for sure is that in the 50's and 60's before emmission controls were important, virtually every car - foreign and domestic - came from the factory with a 180 stat. So that's a hint that 180 is the ideal balance of power, economy and durability

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Not necessarily. Many top racing engine builders say that a bit hotter is better, like 210 degrees. That is, if intake air temperatures are as cool as possible and detonation is not occuring. Heat = efficiency in the combustion chamber.

 

[Patman]

I believe the best horsepower is made on an engine that has a very hot bottom end and a very cool top end. This is why in theory the reverse flow cooling system on my LT1 is supposed to be good. It allows for a higher compression ratio (10.5 to 1) without detonation, since the heads get the colder charge of coolant first, then they hit the bottom end and are hotter, so there is a better combustion with that hot bottom, and less friction.

 

[MolaKule]

I posted this answer before, but I had a Chevy SB in which I ran a 180 F thermo and carbon deposits built up on the valves very quickly in about 30,000 miles.

 

[Dominic]

Does running a vehicle's coolant at 160-170 vs 180-210 make a difference in how well the oil is able to lubricate the engine? (i.e. running a functional 160 stat vs an 180 or 195 in a vehicle with a large enough radiator that the thermostat can do its job?)

 

[monarch]

I doubt it because any weight oil is nearly
as thin as water at 160 degrees.

The main potential problem with running a 160 thermostat is gradual spark plug fouling.

In the 1970's Toyota used 190 stats in cars
it shipped to cold climates like Canada, 180 stats
to mild climates like the USA and 170 stats to
hot desert climates like Saudi Arabia and Kuwait.