Can your engine run too cool?

[acindrich]

My car has a stroked 302 in it and I drove it yesterday, mid day, in 94 degree temperatures on a round trip journey of about 90 miles at freeway speeds. It's a Kirkham car with their standard water cooling set-up (radiator, hoses, etc.) but has a remote oil cooler as well. My water temp pegged at 92 degrees the whole time but my oil temp I had a hard time getting past 70 degrees. I drove it last night at dusk and was getting a reading of about 65 degrees on the guage. If I go up the canyon it also barely moves. I've heard that oil that is too cool is not viscous enough to be effective. Is this anything for me to worry about? My little brothers 427 car essentially runs with 90 degree temps for both water and oil. I'm convinced that with harder driving I can get the oil temp up and I do if I run around in third gear all the time. But for just daily driving on the freeway should I be concerned that the oil is not "hot"?

[Got the Bug]

Your water temp looks fine, but the oil temp definitely needs to be higher for optimum engine life. If you're sure that your gauge is accurate, you should try blocking the oil cooler off with a piece of cardboard to see see if that brings the temps up. If that works, you might want to think about bypassing the oil cooler altogether (it might be needed if you want to track the car though).

I see some pretty big fluctuations in temperatures in Northern California between the winter and summer, so I've been blocking the oil cooler off with a thin piece of rubber during the cold fall/winter months and removing it during the spring/summer months. Seems to work well to maintain a steady oil temp.

[bobcowan]

Yes, it can run too cool. That's the reason for the thermostat, to keep the temp up above minimum. Generally speaking, it should be more than 82*'ish. 90* is just about perfect for both water and oil.

Oil has an operating range, generally accepted to be above 82* or so.

[jwoodard]

65C is only 149F, rather cool for oil. If your temp gauge is accurate, you might consider installing an oil cooler thermostat. Until your oil temp reaches a predetermined level, the thermostat keeps the oil circulating back to the engine and not through the oil cooler. After it reaches the set level, it then circulates the oil through the cooler. I have a Canton unit in my car which is set to open to the cooler at 100C. Works great.

[Ron61]

I believe a lot of that depends on the engine build. Mine ran and made the top power at around 220 water temp. Also notice that when it is cool NASCAR will block off most of their air flow to get their engines up to around 220/230. I have ran mine that way as it came from the factory running that type of temperature and is 41 years old now. I can feel the drop in power when I run it in cold weather and the water isn't above 180.

Ron

[jopper]

I ran an oil cooler on my first engine for about 10k miles.
Whenever i pulled the valve covers to adjust the solids it always had a slimey oiley emulsion all over the place. I believe u need to get the oil up to temperature to evaporate the water that is in the crankcase. Otherwise the oil and water will whip up into an emulsion that decreases oil film thickness. You should disconnect your oil cooler and just have it for looks

[cobraman428]

Yes, an engine can run to cool. Temperatures around 200 degrees F. or hotter are ideal for proper combustion of the fuel. Drawing cool fuel into a cool running engine decreases efficiency with fuel combustion resulting in poor gas mileage. You need to run a thermostat IF what the temperature guage is telling you is correct.

[cobraman428]

Oh yes, a cool engine is a sludged up engine....Yuck !!!

[jopper]

put some oil and water in a blender and you will get the same thing

[StreetSnake]

I had the same problem all the time. I installed a canton oil thermostat and problem solved. Its the expensive way to go but looks a lot better than cardboard.

[Night Enforcer]

To maximize high performance engine life, the oil temp needs to be over 212F to boil off moisture and other contaminants. jopper's comment is right on. If the car sits for a long, long period of time it is really important that the oil get up in the 212F range. I have a Canton oil thermostat on mine too.

[twobjshelbys]

Now that my water pump is working and the oil cooler isn't the primary engine cooler the temps are more in line.

On a normal drive the water temp gets up to about 80*C. In "town driving" the oil temp will eventually climb to about 70*C - 10*C below water. The longer I go the oil catches up, and at a steady running condition of about 3000RPM-3500RPM ( 75-80MPM) the oil will get about 90*C.

I think the message is that these are not commuter cars. You really have to take them on a 2 or 3 hour drive to "warm them up".

My favorite drive is now from Lyons up Hwy 7 to Estes Park (with a side trip in the park weather permitting) then back down Big Thompson Canyon - and put it in neutral and rev it through the narrows). The sound off the walls is classic muscle cars reverberation. I wish I could rent Hwy 34 through the canyon for about an hour.

[acindrich]

Thanks all for the replies. It sounds like the Canton brand bypass is the way to go. Hope I haven't futzed anything up running it for 1500 miles that way. I've got one on order. I too agree that it is the expensive route but does have a little more flash than a piece of cardboard. I did put the cooler in for track day up at Miller Motorsports Park. Dave seems to have track day in the middle of summer and temps will skyrocket then.

[bobcowan]

Be aware of how the thermostat operates. When cold, the valve is mostly closed and about 10% of the oil passes through the cooler. The other 90% is routed back to the block. When hot, the valve is mostly open and about 90% is routed through the cooler. The other 10% is shunted directly back to the block.

It's done that way so all of the oil warms up at the same rate. You wouldn't want the valve to open, and suddenly get a slug of cold oil into the system.

The down side of this is that when it's cool out (or cold), the oil still won't warm up. I used to keep mine covered with duct tape during the winter. That helped, but some days it just would not warm up.

[Got the Bug]

acindrich,

It's very possible that you don't need to run an oil cooler at all on your car. My suggestion for using the cardboard, was a temporary fix/test to see if you could get the oil up to temp. Thrown a piece of cardboard on the car and see if you notice a change.

During the winter months, I run a thin piece of black rubber mat with some holes drilled in it. You wouldn't even notice it unless I pointed it out. As Bob mentioned, the oil thermostat may not work if it's extremely cold out.

[PANAVIA]

The rubber that Doug mentions is available as "Black Rubber Diaphram Sheet" at OSH or your hardware store. 1/8" thick will do the trick.

Steve