Probably , the real concern is to get the oil up to 220 to get the water out. Oil runs about 40 hotter than the oil. A too cool engine tends to sludge.
When emissions control began, OEM thermostats went to 195 and have since gone to 210 or so, with no apparent I'll effects. As long as the cooling system components are capable of the increased temps, and corresponding higher pressures, you should be able to run hotter safely. Modern oils are up to the job as well. Ray
Different age people will have different answers. I'm an old fart and I grew up with the opinion that 180 was the optimal operating temp. With the pollution crisis higher temps became more normal. They used to put temps on factory temp gauges. They no longer do that. Now it's just a safe range. It scares the public when they see that their auto is operating above the sea level boiling point. My hotrods are not going to melt the polar ice caps. I want at least 180 and don't panic up to 195 on the highway. JMHO
The higher temp thermostats let you lose less heat to the cylinder walls so are more fuel efficient. But we are talking 1-3 pct. A 180 is probably as low as you want to go, 195 is likely a little better. Like I said the major hurdle is getting the oil over the boiling point of water. This allows the water and acid to boil off. Since we are only guessing I think 180 is ok, 195 is a bit safer. On most oil life algorithms you get life deducted if you don't reach operating temp. So each start deducts some life, but some gets added back once the engine is warm. jm2c Hoop
I'm like Tommy, us older guys start to worry when the gauge gets above 180, but the newer cars run hotter. My daily driver runs between 210 and 215 and the dealer says that is normal. Boat motors used to run a 142 thermostat but now run something more like 160, and boat motors are now running catalytic convertors too. But I still like to keep my hot rods in the 180 range. Don
The Small Block Ford in my 29 Pickup had a 197* Thermostat and poor Oil pressure @ idle,I changed to a 180* Thermostat and picked up 7-10 Lbs. Oil Pressure @ idle
An oil temp gauge would let you know where 220 is relative to water. 220/240 is ideal 270 is too high for conventional oil. If the oil thins out at 220 you need a different viscosity. Jm2c
On the subject of oil pressure vs heat, just yesterday I called Mercury Marine because my customers have been asking me why Mercruiser is now recommending 25-40 oil for use in their boat motors, and I didn't have an answer. The tech at Mercury said they find that a lighter multigrade oil like 10-30 breaks down under load so they now recommend the 25-40. He said their recommendations are as follows: Best is 20-40 full synthetic. 2nd best is 25-40 synthetic blend. 3rd best (if you are not going to use their brand oil) is to use a quality/name brand STRAIGHT grade oil like 30 wt...........not a multi grade, like the 10-30. Don't know how factual that is, but it is only their recommendation. Don
The latest issue of Street Rodder had an excellent article about cooling. It's one of the better articles I have read in a while because they aren't trying to sell aluminum radiators over copper and it's filled with other useful facts. They say 180 degrees is perfect.
Mt 47 Chevy 216 straight 6 is a 160* thermostat, as per original with a no pressure radiator cap in a fresh OE style radiator. It runs a four blade fan and no shroud and reads about 175* on the gage at most times including 90+ temps in stop and go traffic. I am guessing that the 160 is probably too low for the modern fuels and the above mentioned old sludging. Since I am seeing a 15* difference I am beginning to think that a 180 will get me to 195 on the gage and that should be OK? Should I switch to a pressure cap? Opinions appreciated.
If your 400sbc is non emission and runs at 180, you should feel very satisfied. Most 400 are known for runnin hot. 180 is ideal for non emission cars...
Damn, I must be a borderline "old fart" 'cause my first thought was "what OTHER temp would you want to run?"!
According to Chevrolet you need 200-210 water, and 220 - 230 oil. Anything cooler you are giving up a small portion of power and economy. Oil temps below 170 are damaging to the oil. Temps over 260-270 are too high for non-synthetic. Circle track racers: "Running higher coolant temperatures makes sense if you can control it, but what effect does the higher temperatures have on oil temperatures? Evans' answer comes from his testing with Detroit's automakers. Evans said, "Chevrolet is now saying we should be running the oil temperature at 220 to 240 degrees. If you're not, you are giving away horsepower. We have learned to stay below 260 to 270 degrees because the life of the oil starts to fall off. The people who run 180 degrees need to know that it is not good for the bearings. The oil is too thick. The rings are plowing through it and the pump is pushing it, both of which rob horsepower." http://www.evanscooling.com/articles/aug97ct.htm "For the best performance, water temperature should be in the range of 200-210 degrees F...The temperature range of the engine oil should be 220-230 degrees F." http://www.circletrack.com/techarticles/1822/
I must be an old fart too because I think 180 degrees is just fine. I also run a generator and a mechanical fan so that really makes me an old fart.
Drag racing, I get my best performance between 160 and 180. I get the whole fuel atomization thing, but My engine at 180 ran better then it at 220...But who knows !!
My rebuild manual shows a graph of engine wear measured at different temps, and it shows that the higher temp has less wear. Below 180 it increases a lot. Above 200 it flattend out. So yea 180 is the minimum, better for power. 195 is better for wear. Yea boats etc run at 165 or whatever they are pretty high horsepower and do it continuously. Lifetime isn't so much an issue. Most folks get bored of their boats long before cylinder wall wear is an issue. (actually with cars too, I think not many people buy a new car and actually drive it the 300k-400k miles or whatever it takes to wear out the cylinder wall) Sent from my Verizon 4G LTE smartphone
Don. I have been running big block boats on the lower Colorado for more than 30 years. I have never used anything other than straight 40 on a boat that was cooled by lake water. Sometimes the ambient air can exceed 120 degrees in summer. In shallower lakes like Lake Havasu, in July and August you have to go down several feet to feel refreshed. Even after a full throttle blast, in a 500 horse 468 Chev. water temp seldom exceeds 195, Oil about 235. Just about any conventional single viscosity oil will remain stable up to 260. I don't know anyone who uses multi vis in a lake cooled boat. Why Merc. would recommend it seems strange to me. I know you are probably talking ocean water but still...
I just got home from work and grabbed my IR thermometer, point it at my 460. Got the coolant temp at 180 and oil temp at 190. I'm suprised at such a modest difference since I have a high volume oil pump (which I do NOT recommend) I usually run the lighter oils, 5w20 or 10w30 depending on what's on sale. Anyway I run a 180 thermostat and have 212k miles on this engine, no problems.. Sent from my Verizon 4G LTE smartphone
Don't sound so defensive about being an old fart. I'm kinda proud of it...it sure beats the alternative.
It really doesn't matter how hot you run. Pressure and boiled water, not temperature are the culprits. If you can run a higher pressure cap you can squeeze out more degrees before you boil over changing the specific heat of water from 4.19 to 2.1 causing the engine to ping if it has any timing at all.
The Jalopy Journal
