Can you over cool engine oil? I was wondering about installing an aftermarket oil cooler along with the factory oil cooler to lower oil temperatures. I understand that lower oil temperatures prolong the life of oil, correct?This would also help to add more volume to the system. The only problem I could think of would be boil off of condensation. Thanks for any advice or information on this.
Engine Oil Cooler
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Patman
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I believe most oil coolers come with a thermostat, so you won't have to worry about the oil
getting too cold. Ideally it would be nice if this thermostat didn't open until the oil temp got up to about 240 or so. I'm honestly not sure what temps these oil cooler thermos open up at
though. One good thing with an oil cooler is that it should actuallyl heat up the oil faster after
a cold start.
MolaKule
Staff member
Actually, the oil heats up slower in cold weather if the oil cooler is one of the tanks in the radiator, according to my '92 Burb. The RATE of temperature rise is faster, however, once the thermostat opens.
quote:I would agree with that. Personally, I can't see a lot of justification for a cooler. The peak oil temperatures are probably not going to change a whole lot. That coupled with a greater potential of oil system failure due to extra stuff and possible loss of pressure makes this a risky choise IMHO. In my humble view a synthetic or blend such as Shaeffers makes much more sense. These oils are proven to be viscosity stable for extended periods. If thats not satisfactory switch to a 40 wt or add a bottle of 15W-50 to existing 10W-30. (Thats what I'm doing)
Originally posted by MolaKule: Actually, the oil heats up slower in cold weather if the oil cooler is one of the tanks in the radiator, according to my '92 Burb. The RATE of temperature rise is faster, however, once the thermostat opens.
MolaKule
Staff member
Another application for a 5W30 either in synthetic or a blend with Moly.
Patman
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What kinds of oil temps do you guys think are safe to run? I believe most f-bodies like mine typically run 225-230F. My car was supposed to have the OEM oil cooler since it's equipped with the optional 3.23 rear end, but GM messed up and my car didn't get it. I hear the oil cooler is troublesome on the LT1s anyways, so it worked out well for me I guess.
That sounds pretty high. And to think, some people are probably running 5w30 dino in those engines, thanks to GM's asinine recommendation due to CAFE.
I believe 195F is the ideal oil temperature. At least that is what Dave at Red Line told me...ideally, that should be the temp at the cooler outlet (if present).
My oil sump temp varies with ambient. It has a oil to air, stand alone cooler from factory. I'm running ~190F once fully warm in the summer. In the winter, if I drive easy and not on highway, it only gets to ~175F. I have yet to get it too much above 200F no matter how much I abuse it. Don't have much opportunity to run it extremely hard for a long time on public roads though. The cooler thermostat completely opens around 220F.
Personally I don't think I would even run a 10w30 in that motor if that's the kind of oil temps it sees regularly. Maybe in a synth only.
Patman
Staff member
195F? If the oil runs that cold how is it gonna burn off moisture?
MolaKule
Staff member
The data I have seen show an ideal oil temp in the sump should be about 170 F with a maximum rise of 20 C or 68 F, which gives about 238 F maximum oil temp. The oil coming off engine parts is much hotter, so moisture should be evaporating when oil temps go over the
210 F mark. Due to a partial atmospheric pressure in a crankcase with a well functioning PCV, the evaporation temperature for water should be slightly lower than 212 F.
Well, just venturing a guess but water will still evaporate fairly quickly at 195. Just because it is not boiling doesn't mean it won't burn off.
But also the 195F is sump or after cooler and it will have cooled by then, there are many other areas of the engine that are over 212F, for example:
http://www.vtr.org/maintain/lubricants-redline.html#limits
quote:The number I have seen is oil life decreases by 50% for every 12-15 degrees over 150 degrees F. As far as water boiling off- I get considerable drop in my swiming pool level at 86 degrees where it is now.
Originally posted by Tommy: Is there not a rule-of-thumb that says oil oxidation will increase by whatever amount with every 10-degree rise in oil temp.....MolaKule? I realize it have to be a pretty rough guide, to allow for the different types of basestocks etc.
![[Big Grin]](images/icons/grin.gif){kind=icon}
My sons 2.2 Cavalier runs as high as 229 F in Summer. Thats probably pretty close to oil temp out of the engine.Oil needs to be at the correct warmth. Oil that is too cool will not properly lubricate your engine. If you install an additional cooler, always install a thermostatic control valve. This one is 180°F. (For ATF I'd like 160°F.)
http://www.bmracing.com/products/acc_engOilCoolers/thermoControl.html
I wouldn't like 240°F--too hot. In any case, in those Wisconsin winters, proper lubrication with cold oil is the challenge.
Ken
[ August 13, 2002, 12:11 PM: Message edited by: Ken ]
Again, this is one of those things that depends on the application. I really don't believe an oil cooler is necessary on a lightly loaded relatively big cube OHV engine. On a high-strung 4 cylinder or a turbocharged motor, or a vehicle that sees much high speed or towing, I feel it is a viable option. Yes, you can over-cool oil, if not using a radiator tank mounted oil cooler, I would definitely use a thermostat.
MolaKule
Staff member
I think we're talking about is keeping the oil coil enough that it will cool the bearings and rings
and keep oil oxidation bay, say at or below 200 F, if possible. Cooling the oil too low wouldn't allow evaporation or the boiling-out of moisture.
I too have been "kicking around" the idea of adding an engine oil cooler to my car. Derale makes a nice unit with a thermostat in the "sandwich" adapter which prevents the oil from flowing to the cooler until it reaches 180°F.
It seems to me that cooler oil should reduce the temperature at critical locations within the the engine (cams, main bearings, connecting rod bearings, etc.) and it "should" also reduce oil oxidation and sludge buildup. Are these assumptions correct or is an oil cooler more trouble than it's worth?
BTW, I drive a 2001 PT Cruiser (2.4L I4) primarily at freeway speeds (65-75 mph, 3000-3500 rpms). I live in Wisconsin where the temperature ranges from -20 in the winter to 90+ in the summer.
Thanks in advance!
![[Patriot]](/forums/graemlins/patriot.gif)
I would also agree that 240 is too hot.
I have the Corvette oil temp sender wired up on my '96 Impala and I can monitor oil temp via Scan tool (I didn't add a gauge but I can read and log the temp with a scan tool from the sender -- the logic is in the PCM just GM only added the sender on the Corvettes).
In stock form the engine oil temps are 190 to about 225 degrees. These temps are with the factory 9C1 police package oil to air cooler that I installed in place of the OEM in radiator tank cooler.
Now I'm running a stroked small block (396 cubic inch LT1) in this car. I ran it for a couple of months without the oil cooler (due to interference with an aftermarket oil pan) and I saw temps of 225 to 245 (which was too hot for me).
I have now retrofitted the '93 style police cooler to my '96. This setup uses a straight filter adapter and takes a PF25/35 filter instead of the smaller PF52 and uses different lines into the same '96 police cooler. Using this setup my stroker is back to the 190 to 225 range and most often runs 200 to 205 with 225 temps seen at the drag strip.
Coolers are good but you can go too cool. Heat is necessary to burn off the condensation and other junk in the oil.
The PT Cruiser, IMO, features an overworked 4 cyl engine that is a prime candidate for an oil cooler.
How much cooling would one get with a well-placed bypass filter - would it be significant?
MolaKule
Staff member
Unless you put large fins on the filter and placed it directly behind the radiator, I don't think you see more than a 1 F drop.
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