Zero1Niner

Been having problems with the oil temps creeping up when I am driving on the freeway more than 70mph ish. It will creep up to 250, and slowly continue past 250 if I drive longer distances at the higher speed.

I had a 195* thermostat in the car, and the coolant temp was staying pretty locked in to ~200*. I thought that perhaps by reducing the coolant temp, it might help keep the oil temps lower, so I installed a 180* thermostat, and now the temps are solid around 180, but the oil temps still creeping up...albeit more slowly now.

As soon as I get back below 50mph, the temps start dropping. Around town the oil temps stay cool.

Anyone have any suggestions on what I can troubleshoot on high oil temps @ high RPM?

jb78L-82

Can you describe anything you have done to the motor recently that may have changed the oil temp? Tune up, timing change, cooling system changes, carb adjustment, exhaust etc. What did the oil temp use to run? The oil temp gauge reads from the sender above the oil filter, not the volume in the filter or pan, so the actual oil temp volume in these 2 areas should be much lower than the temp on the gauge with the 12 0'Clock position (250 degrees) being the "normal" operating temp on the highway, lower around town. Have you verified the actual temp in the filter housing and oil pan using an infrared thermometer for accuracy of the gauge? I installed an 81/82 oil temp gauge in place of the clock in my 78 L-82 30 years ago and the normal oil temp is between the first hash mark on the gauge and 250, depending on the temp outside and whether I am driving on the highway or around town, with the highway driving and 90 degrees outside temp causing the gauge to be closer to 250 degrees, oil pan temp closer to 200-210 degrees. As long as the coolant temp is between 180-200, I would not be too concerned.

doorgunner

Have you tried different brands of oil filters to see if the temp changes much?

Doe the temp creep up when the oil has 75% or more wear on it (between changes)?

I recently checked my oil pan temp with an infrared gun....once the engine reached operating temp and the car was driven in traffic and at 60 mph the temp read 250`F with a coolant thermostat of 180`F....if I went through a rainstorm the temp dropped to 220`F. The same thing happened to the oil tank temp on my Harley engine which is air-cooled. Also the oil pressure rises 5-8 lbs at idle during a rainstorm...which shows me that an external oil cooler would be a big benefit (aftermarket motorcycle vendors offer an oil cooler with a built-in thermostat to keep the oil at a constant temp).

I think I'll check out the Jegs site.


Edit: I'm back......never mind....$360 or an electric/oil cooler.....I'll just plumb a trans cooler behind the radiator and connect it to the engine oil passages to keep the temp constant even in cold weather. By the way....the oil in my Harley looks/feels much better after 3,000 miles with an in-line oil cooler.

mikem350

Running too thick an oil or with thickening additives is not good. Go to a synthetic 10w-30 and forget about it!

This is based on your coolant temp and oil pressure being normal. Your car w OD trans and 2:73 rear barely idles at speed

Zero1Niner

When I first bough the car, there were cooling issues. I had the chance recently to attempt to upgrade a bunch of stuff on the car. Here is what was done. New aluminum radiator, new electric fan setup (and of course removal of the engine driven fan), new hoses, new thermostat, plugs, wires, cap & rotor, o2 sensor.

I have not verified the temps. Just referencing the gauge. The worry is that its been cool here lately. Not fighting 90+* days, which will be here soon enough. If I am just cruising around downtown, it sits right where you described between the 11 o'clock position. Once I get on the freeway, and get above 70+mph, then the needle starts creeping its way up to and starts to pass the 250 mark. Coolant stays @ ~180-190. Im worried im gonna see this get a lot higher on the 90+* days and cook the engine.

Zero1Niner

I have not made the switch to synthetic yet, but I am running 10w40 now.

In another thread, I am working on a trans swap so that I am not taching at 3,000 rpm's when I am driving at ~80mph. That sucks. Who the hell at GM thought that was a good idea? I guess thats why they switched to the 700R4 in 1982.