The Stovebolt Site Forums The Shop Area Engine Shop Let's revisit engine oil cooler

If I remember my science class correctly, when oil gets hot it thins out and pressure drops. So would it be correct if you cool the oil thru a cooler, the pressure will rise again?
Thanks
Sharon

No. Getting the oil hot enough to make a big difference in pressure would be getting it far too hot, along with the rest of the engine, to be in the normal operating range. The reason an engine loses oil pressure at operating temperature is due to the expansion of parts that carry the pressurized oil, such as the connecting rod big ends, main bearing caps, etc. If you ran the oil through a sub-zero freezer on the way back to the oil pump, there might be a noticeable difference in pressure, but any benefit from a room-temperature cooler is pretty much imaginary for a stovebolt engine.

If you're running a midget 4 cylinder with dual overhead camshafts and a turbocharger, and winding it up like a bumblebee on steroids, an oil cooler might be a good idea. On a stovebolt engine in street trim at anything resembling stock horsepower, it's just stupid.
Jerry

Jerry, I get the message. I'm just overthinking things. I should just be happy with a good running truck. You do have a way with words.
Sharon

No disrespect intended to anyone but I love hearing someone say "it's just stupid". Personally I think we should say/hear it more often to keep common sense alive and "common".

No disrespect to anyone intended, and I hope my blunt comments don't get misinterpreted, but after close to 60 years working on these old rigs, I tend to draw a pretty distinct line between what's actually beneficial, and flights of fantasy. I've run oil, transmission, and even rear axle lube coolers at times, but they've always had a specific purpose, like keeping a race car engine together that's running 250% of its original horsepower, or keeping the gear lube temp down on a sports car rear end that's negotiating 20 high speed turns a lap on a road course. Doing race car stuff on a street vehicle just doesn't make good nonsense, most of the time.
Jerry

Thanks Jerry, one of many thankful you are here...

Regards,

Cosmo

Cooling the oil prevents it from breaking down and losing its lubricating ability. Remember oil does two things: lubricate and cool the engine.

Pumps create oil flow. Restrictions create pressure (and lack of restrictions create no pressure). That's why one of the signs of a worn out engine is low oil pressure.

Oil/transmission/rear end coolers are for vehicles under heavy load like towing or continuous high output. Removing the extra heat allows it to operate much longer at high output than if it was not removed.

I wouldn't bother with an oil cooler on my 235. If I were to though, I would incorporate a thermostat to bypass the cooler until it got up to temp. That is how I have my Morgan setup. Cold oil is not your friend either.

Dennis