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Engine oil coolers and longevity
Wondering if an engine oil cooler is worth the investment for engine longevity. Also those of you running them how do you keep the rubber hose off the headers?
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If one was building a car that was going to see high rpms for long lengths of time it would be a good idea. For your average hobby car not worth the trouble or even needed.
For example my current engine is hardblocked..filled to the bottom of the waterpump holes. My biggest concern with the shortblock was how to control oil temperatures. I was ready to dive into oil coolers,remote filters,thermostats and the lines and fitting. Someone suggested to just see what it does for oil temps. As far as normal driving my oil temps normally sit at 210, around town they creep up once in a while to 240 and also down the highway at higher revs in the 3000rpm range they will creep up to 240. Which from what I understand with synthetic oil shouldn't be an issue. What is interesting with running a oil temp gauge you really see when your engine is truly warmed up and it takes a while for oil temps to get to 210. |
I've data-logged my motor substantially, i've got engine oil temp as one of my inputs to the EFI computer. Before hardblocking the engine the oil would sit at about 100*C (212*F) on local street driving, after an extended drive on the freeway, would creep up to about 110-115*C (230-240*F) then cool back down when the rpm dropped. After hardblocking the temps rose about 20*C everywhere, so I put an oil thermostat (85*C) and an oil cooler on the car, now the oil is at basically 95*C-105*C everywhere.
IMO, unless you're grout filling the block, move along, nothing to see here. You want the oil to get up to temperature otherwise you'll be changing it every 3000miles. |
I ran a block filled to the freeze plugs for 90k miles on the street, abusively, and many many long trips, never saw over 300F degrees. Use quality name-brand oil, change it on regular intervals, and you are good.
If you're concerned about it, you can help by using a larger capacity oil pan. That should be good for a few degrees. As for lines, routing, and headers, the best way to plumb is tap the block itself, and don't use an adapter. Then use pipe threaded fittings in the block. That's as close as you're going to get with clearance. When you go to remote filter/cooler setup, there are other concerns, such as potential for leaks, hose replacement intervals, line size impact on flow/psi/etc, drainback/refill time, bypass, and filter types to use. = Headache for little to no gain. . |
I think you WANT the oil to get at least over 220f to boil off any water. As long as you keep it under 250f I think you are fine.
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FWIW, I used to do track events in my C6 corvettes and would watch oil temps. The computer will not through the engine into limp due to oil temps until they reach about 305 degrees. I've seen as high as 300 on a 100+ degree day about 15 minutes into a 20 minute session on that car. Base C6, no oil cooler.
Now that type of situation on a large bearing pontiac engine is going to create more heat, but my broader point is that the engine protection strategy of the GM as delivered computer doesn't kick in until above 300 degrees for the oil they recommend (mobile 10/30). So normalized temps in the low 200's are fine. If you're consistently seeing temps at or about 250 you just want to change the oil at earlier intervals. My example above would be fairly extreme for most of us here with out cars, but it's understood that if you're at a track event like that, it gets a fresh fill before and after the event. |
Keeping the oil warm (over 212°) and the coolant cool is going to produce a happy engine. I still have an oil cooler on the drag car, but removed the oil coolers from the street cars. During the cooler weather the oil just wasn't getting warm enough to purge the moisture.
The other thing I found out was you stick a monster engine oil cooler along with a monster trans cooler, and an A/C condenser in front of your radiator and they do a pretty good job of stifling airflow. Coolant temps dropped 20° by eliminating the oil cooler and going to a smaller better suited trans cooler, and engine oil temps didn't go up that much. |
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On a cold start, the water heats faster than the oil which causes the cooler to actually warm the oil. After warmup, it's the opposite situation. Below is the setup on my '66 GTO. It's a C4 Corvette unit (made by Modine) attached to a 90deg adapter via a simple adapter plate on a Firebird long-branch adapter. The hoses connect to the heater nipple on the RH head (although mine takes water from both heads) and then to the heater core. The switch (used to) control the electric fuel pump and also turn on an oil pressure idiot light (with rally gauges and solid rollers, you can't hear/easily notice if there's low oil pressure). This cooler also allows (forces?) the use of SBC oil filters. Unfortunately, with Doug's headers I have to use a shorter filter than that PF-35L (it worked well with H-O Racing's Tri-Y headers). If you want a CAD file of the adapter plate, shoot me a PM. https://www.pro-touring.com/attachme...1&d=1245467283 |
Conventional oil should be changed if the temp gets over 270 degrees. Most oil temps are about 20 or so above water temps. At a NASCAR race there was a car that finished the race when was a problem with an oil cooler. The oil got so hot the driver sustained burns on his back (where the oil tank sits). The synthetic oil got so hot it didn't register on the temp gauge.
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oil temps
I drove my 421 SD on the street with an 8 quart SD pan with only 7 quarts and a 390 rear end. spinning it up there on the freeway. Never got over 230 on the oil and about 190 on the engine. Ran Pennzoil 30w. FWIW
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IMHO Not necessary except for extreme duty,or extended RPM, applications.
Monitor oil temp after in service and determine if use necessitates. Coolers can and will cause drop in oil volume. You need a pump that is up to the task you demand from it. KIS Good tips on minimum oi temp given!! |
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I have never looked at oil temps on any street engine.Drove 2 short fill pontiacs on the street and just played dumb and ran 10-30 mobil 1.The engines are in other cars and I have never been told of a issue.FWIW,Tom
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I don't watch it in mine either. My car gets driven longish distances at rpms exceeding 3000, plus beat on quite a bit. I change the oil every spring and it's always clean and in otherwise good condition. If I had to guess it probably runs 230ish on a hot day in the summer when the car runs about 195 on the coolant temp.
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I'm building mine for similar duty, hope to run into you one of these days once she's finished! |
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That doesn't seem like a big drop in hot pressure after a hard run to me Nick.
You could likely and very simply just change oil brand or viscosity of the oil and see those minor pressure differences change. 5-7 lbs. change when hot wouldn't bother me, as long as your hot idle pressure isn't ridiculously low to begin with. I used to run VR1 20-50, and I would see hot idle pressure drops that you mention just from a 20 mile highway cruise at 3,000 rpm, and would consider that pretty normal. Switched to Amsoil 20-50 many years ago and haven't really noticed any pressure drop hot or cold which leads me to believe (and it's been mentioned to me before) that this oil is likely holding it's viscosity better. |
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