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IO,
Well I don't think we have enough time here to teach a class in Thermodynamics but here are a few facts to think about.
When oil heats up it's viscosity will decrease. Engine oil does two main things, lubricates and transfers heat away from the lubricated part. Having to much oil pressure is just as bad as not having enough....reason is that you need the oil to move through at a speed that allows the heat to be taken away and still do its lubricating job.
Oil is designed via various base stocks to reduce friction at a normal specific operating temperature range's. Normally oil likes to operate about 50+ degrees above water temperature. Take it out of its designed range and it breaks down and can no longer perform notwithstanding that the block and associated parts become heat sinked which allows greater clearances that the oil can no longer protect. Add various additives and the oil can work in almost any temperature environment.
Not to bore you but the design of oil is quite complicated in the since that in the multi grades its designed to first while the motor is cold run like water to lubricate all the parts before damage occurs. This is also part of the bypass oil filter system so that oil gets in the motor quickly.Then the oil thickens up as temperature increases to again provide that envelope of protection. Take it out of its happy place and there is Limited protection and damage occurs.
Hope that helps a little.
I race drag cars and I am forever chasing lubricating problems, we actually try to dry the motor up internally for two reasons, one is parasitic drag created by the weight of the oil and the other is combustion contamination caused by the oil during the firing cycle. We run Dry sump systems along with crankcase evacuators that suck negative pressure in the crankcase. Because of the lack of oil in the crankcase we use a lot of high tech coatings on piston skirts and wrist pins to make thinks live longer.
Glad you did not get to bored on the subject. Yes, on your statement as long as the upper range / temp is not exceeded.
Again as it reaches that top range it looses its viscosity but more importantly it looses its ability to cling to a hot part or hot cylinder wall, that's when damage occurs. Keeping that proper balance with a good cooling system and even perhaps some external oil coolers are a good Idea if they can be built into your vehicle.
Years back when I built that Buick V-6 I also built a kick-out pan which added two quarts to the system. Mostly done to use the extra volume and extra area exposed to the air as a heat sink.
Will I think an oil cooler is a great Idea, but first ask yourself do you have a cooling issue with you motor?
Average engine water temp is 185 degrees , of course new cars run them higher for smog reasons with higher water pressures
Average oil temp is normally 50-60 degrees above water temp.
Now don't take any of this information as the Holy-Grail! because depending on equipment every vehicle will act & cool a little different, and we all know that Jeeps have a Limited radiator opening, plus add a winch and you have really no air coming through.
If your radiator is large enough and perhaps has a good cooling fan and has been able to keep up temp. wise while your Idling around on a hot Texas afternoon, you may need nothing.
The guys with auto transmissions that are using the lower tank in the radiator for some Transmission . cooling are probably at a greater risk by adding heat to the radiator via there Transmission .
If your concerned get an oil temp gauge and put it in the system...........the problem with oil coolers in a Jeep is finding a good place to put it that has access to cooler air and will not get knocked off.
Like I said in my Jeep I added 2 quarts to the pan.........in a since an oil cooler! The other thing I'm going to do is perhaps stick some louvers on the hood...........get some of that heat out of there.
On the reverse if you do anything in the winter then you may have to figure out alternatives to decrease your cooling ability so that you can get some heat built up.
Everything is a compromise.
The oil cooler may be over kill or not. With an electric fan with thermostatic control and of course the coolant thermostat controlling water temperature I would say there was a pretty good chance that the engine temp could be held right at 180-190 deg F with not too much problem.
I have seen coolers that connect to the oil filter tap that will allow a remote mounted filter and a cooling coil to mount on the fender or fire wall. How bad could it be to have a filter someplace that didn't pour oil on the passenger side motor mount every time you changed the oil?
I would agree on that remote oil filter and if you want to add a little cooler along the way all the better..............Earls has a pretty good selection of lines, fittings and such.
On a separate note tell me about your 140 Amp Alternator? I have the old Delco 10SI or could be a 12SI 63 AMP and will be looking to upgrade.
Every inline 6 jeep put in a CJ could maintian oil pressure as the engine wore. I have a AMC 258 i6 / 4.2l with the same problem. i put in a quart of Lucas brand oil everytime i change my oil. It's expensive but it keeps my oil pressure a few psi higher.
