Oil temp monitoring

[dyeager535]

Yes, you can buy gauges that do this. Just fun to see things you come up with work I suppose, and since I had all the parts already, why not. My real goals are to eventually test the efficiency of the oil cooler, and find out if I run it a bit lean, if the oil temp change is significant enough to notice.

Here's the coolant temp at the same time:

Details: at the end of a 15 minute run up a mountain pass at 60-65MPH, towing a utility trailer of approximately 2000lbs. Ambient temp at the bottom was around 40-45*, 33* at the top.

I have a suspicion these sending units (Delco three wire coolant temp sender for both coolant and oil from later year apps) are a bit off for these gauges, as the coolant temp is off the thermostats rated temp, and the ECM also reports a different temp. I'm guessing the gauges are reading around +10* . But I know what "normal" is, and that's all I'm really concerned with.

That is the highest reading I saw for either temp. As the load decreased the oil temp fairly rapidly dropped too. Never saw the oil get back to actual coolant temp, except if I had long periods of low engine load.

Vehicle specs: K5 at about 5500lbs. 19" core radiator, electric cooling fans, factory engine oil cooler setup (early: braided, not rubber, cooling lines), 350 Vortec long block, aftermarket 5qt baffled pan, Mobil 1, 1qt filter, conventional 10W30, TPI, SM465, NP241, 3.42 gears, 33" tires.

 

[Bent77]

Subd for fun experiments

 

[Wes Harden]

So is this pre-cooler control test ?

 

[dyeager535]

No, cooler is already in place. Cooler is sitting in front of the primary cooling fan, so I figure it's about as efficient as it can be. Cooler itself is in good shape.

Unfortunately most likely going to be a long time before I get a chance to remove the oil filter adapter and put a standard oil filter adapter in it's place.

I just looked it up, apparently 240* is the point conventional oil starts to break down. From how far off I think the senders read, there isn't much of a margin to 240* based on the temps I saw. With a 4qt pan and no cooler, I'm betting the temps would be significantly higher. Especially if ambient temp is 40-60* more.

 

[6872xtc]

I have all Autometer gauges in my '70, no oil cooler, roller cam big block, full synthetic 5W-40, but I don't tow with it. I don't think that I have ever seen the oil temperature get over 220* . Idling with the A/C on after driving in stop and go traffic has been the worst since input the oil temp gauge in. Just giving you a reference

 

[dyeager535]

I don't think that I have ever seen the oil temperature get over 220* . Idling with the A/C on after driving in stop and go traffic has been the worst since input the oil temp gauge in. Just giving you a reference

Have you ever run conventional? I can't recall if lower temps in engine oil is one of the claimed benefits. Going to be awhile, but I do have synthetic on the shelf for the truck, so I suppose it would be an easy check.

One thing I don't like about these coolers is that you just assume it works. But the youngest one is probably 25+ years, even if a replacement. I didn't do anything with the cooler prior to slapping it in the truck decades ago, for all I know the previous owner never changed the oil and it's sludged up inside and not working well. Also, I don't believe the little valve in the adapter is really serviceable (staked into the aluminum), and I'm not sure how you'd know if it's working right either. I know I cleaned the adapter as best I could, but it wouldn't be a bad idea to flush the lines and cooler itself. Hadn't considered that possibility...

I hate the thought of disassembling it, it doesn't leak, and I know the odds are against me if I monkey with it lol.

It might very well be that the big block just isn't being pushed as hard, and thus the cooler oil. Dunno, seems quite a massive difference, especially with no cooler. What's the pan capacity on that? 5qts?

 

[6872xtc]

I had Rotella in it previously, I did see a tiny decrease in the oil temperature peak, but only 2 or 3 degrees. It does appear to get there more slowly, but that isn't a proven fact, could be just my perspective.
I saw the decrease in oil temperature on one of our ready-mix trucks after we switched it to semi-synthetic. We used a FLIR camera and tried to check it after a similar work day. But this was after months past the changeover.

You should be able to use a temp gun to find the effectiveness of the cooler on the outside, at least. Check it against the pan temperature as well.

And I believe that I have a 5qt oil pan. Stock 1975 C20 pan. I would bet that you are correct about the gauge reading being off. Could be some misrepresentation on both gauges.

 

[Wes Harden]

Use an ir temp gun, check the inlet an outlet temps should be 20 to 40 degree drop. My stacked plate trans cooler does 40ish degree drop. That cooler was on the truck when I bought it 16-17 years ago.

 

[dyeager535]

Yeah good call. I should have one of those already, they aren't ridiculously expensive last I looked.

I can see the gauge being off, but only maybe 10*. I've compared with the ECM, off a bit, but not ridiculous.

I should keep my eyes open for some inexpensive aftermarket gauges and sending units. I've already got the plastic piece to hold a couple, wouldnt be crazy to get that's set up for this sort of thing. I'd like to check the 241 temps eventually as well, just for fun.