I have a new to me 1986 Corvette convertible 4+3 non Z51 with about 50,000 miles. All stock as far as I can tell. This has been discussed at length I know but most of the searches I have done are from long ago. Here is what I know. My car had been sitting for some time so when I purchased it I performed a fairly comprehensive tune up/service. Changed oil with dino 5W30, installed new AC Delco #5 plugs, plug wires, rotor, cleaned MAF and throttle body, air filter, fuel filter, changed OD fluid and filter,and new Continental ExtremeContact Sports. The car runs and drives phenomenally. I am concerned about the oil temp only because I have never seen a car run this high. The coolant temp stays right around 195-210 in normal driving. The engine oil temp is consistantly around 235-240 in normal driving but has peaked around 255 in spirited driving on the curvy roads in the Ozarks where I live. All of this with outside temps around 80 deg F or below. Would like to get some opinions if this is normal or what steps to take if it seems too high.

 

Moved to C4 Tech.

 

What you need to know is whether the temp reading is right. I suspect it's not. Take an infrared temp gun and shoot it at the oil pan and filter. Could be a bad sender or gauge.

 

https://www.corvetteforum.com/forums...the-cause.html


had same thing. was cat for me.

 

C4s run warmer by design, 255 this time of year is a bit much.

Remove radiator shroud and clean area between radiator and condenser. Well documented issue here that the space plugs up with debris. Verify that t-stat is working, stock is 195F. Verify that fans come on, main fan is 228F (coolant) and if there is B4P pusher fan in front, it comes on at about 10F higher.

Flush out old coolant if you haven't done it before, should be every 2-3 years. If the car feels tired as it heats up or loses power, cats could be plugged up, and they definitely will eventually if its ever been out of tune for a long period before you owned it. Precats will plug up.

 

225 Deg. Oil temp normal driving is fairly normal. I do remember seeing 235 in traffic or running it a little hard even as much as 250 or more when Beating on it.
as said before put a temp gun on it or for piece of mind swap out the temp sensor.

 

Thanks everyone for the replies. I will tackle the radiator shroud next.

 

Your coolant temp is fine in my book. Just give a look from the front under the license plate area you can see the front of the Radiator fairly well. Then go to passenger side were the AC lines come out you can sometimes you can see between the AC & Radiator for a quick inspection and go from there if you take things apart.

 

Unless you are at the race track, And possibly in extremely hot ambient temperature situations,I have found that if the temperature differential between the coolant and the oil is larger than 10°C, there is usually a reason why the engine oil is hot. In my case it was simply that the exhaust good night Miss Kate through clogged catalytic converter. If the car is equipped with a KC4 oil cooler/heat exchanger, I have found that temperature differentials between coolant and oil usually stay between 7 and 8°C.

If the differential is much more than that there is typically a problem. Because your coolant temperature is just fine, I don’t think the issue is in your radiator. But it will be great to methodically cross that off the list as you have indicated you are going to do.

look forward to hearing what u find!

 

OP's temps w/an oil cooler = "not normal".

 

lol at my reply, I was using Siri and I have no idea what the Miss Cate means!

 

I saw that too and knowing that you are not one for miss printing, I think this is what you where aiming for

In my case it was simply that the exhaust COULD NOT GET through clogged catalytic converter.
I use the talk to text all the time for Field Notes and it gets funny

 

I have a factory oil cooler on my 85 4+3. My temps on oil and coolant are normally very close to each other. Oil temp has never been more than 5 or 10 degrees higher.

 

exactly what i have found too. 👍

 

I pulled the radiator shroud and it was clean in between the radiator and AC condenser. I have ordered new direct fit cat and Y-pipe with pre-cats from magnaflow. They offered free shipping so I went with them direct instead of through any of the vendors. Looks like the parts will not arrive before I leave town on a two week trip starting Monday. I will report back in a few weeks when I get the new parts installed. Thanks again for everyone’s responses.

 

Again, I agree.

My 92 has NO oil cooler....like all LT1. It never gets that hot other than track use. It never gets close to that hot on the street. As it relates to oil temp, functionally....they're pretty darn similar.

However, OP, I'd TEST your exhaust system for back pressure before dropping coin on cats.

 

All of them, because of increased friction in/on every component....but my train of thought to your question:
Heads>Combustion chamber>Valve Train>Exhaust Manifold/Headers....lots of heat from increased friction and heat soak! I will point out, oil temperatures below 212°F will allow moisture (H2O-water) to reside within the oil, condensation is constantly being introduced within an operating and non-operating engine block. Oil must reach 212°F (boiling point of water) to "flash" out the moisture!
Speaking of NASCAR, they run 290°F+, special coatings and all the goodies, but 8k+ RPMs for 500 miles, 290°F+ engine temperatures....I wonder what their oil temps reach, but more often than not, not high enough for the oil to fail.
Perhaps you're suggesting aluminum heads/headers to help with heat soak, which I would agree with! Overall though, I feel 200°-260°F oil temperatures on a street driven C4 is normal/acceptable (no oil cooler, either by coolant or air and a cooling system that is functioning properly). I've seen +45°F difference in oil temperature over cooling temperature from spirited driving and oil temperature takes much longer to come back down than coolant does, but remember the oil is in contact with many very hot components that the antifreeze can never reach (bottoms of pistons, valve springs, valves, rods, crank, etc)! If you think about it, oil is actually pretty amazing stuff and peaking at 255°F from spirited driving (especially if it's synthetic) is nowhere near a cause for concern, regardless of the ambient temperatures this time of year (C4 engine compartment holds a lot of heat all the time) Just my .52 cents worth👍

 

When stock my 84 would get into the 240s when you really beat the snot out of it. But it would come down if you were just running along. After the mods a spirited pull would get it to the 250s and I ultimately added an air to oil cooler. I agree that at the given ambient temps however, his does seem to be a little on the high side but nothing to worry about.

 

My car does have KC4 oil cooler. I’ll investigate possible blocked lines as well.

 

https://www-motortrend-com.cdn.amppr...temperature%2F