I know it's been covered before but after reading several threads on the Corvette Forum about what a "normal" operating temp is supposed to be I am a little concerned about my 86. Under normal highway driving the coolant temps are about 195, which is good but the oil temp is in the 230 range and I've been reading that they should be within 15 to 20 degrees apart, not the 35-40 degree difference I'm seeing. I'm using Mobil 1, outside temps are mid 80's and the car is basically a garage queen with just a shade over 21,000 miles on it, a new water pump just installed and fresh coolant.
In traffic the coolant jumps to 210-215 and the oil creeps to 235. I know the fan comes on in the 220 range and the fan works fine. I'm just curious if my temperature difference in the coolant and oil is something i should be concerned about and what I should check for. Thanks for any information you can give me.

Welcome!

Until Andy steps in, let me offer this:

It seems as if your water temp is running a little LOW. That would spread the gap between the two temps. I don't think mine could ever run below 200 degrees even on the highway. One thing to consider is that your oil does not leave the engine block to be cooled like the water does(unless you have the external oil cooler). The oil will always have more heat.

If you do not see oil in the coolant and vice-versa, I would not be too concerned. I am sure Andy(bogus) will step in too and give his opinion.

I agree, the coolant temps seem a little low, perhaps a slow or aging sensor? or perhaps the oil temp sensor has an issue or 2.

As for the oil temps, they will creap up. and when they get there, they stay there.

I would suggest using Mobil 1 in the engine and leave it at that. I know it will deal with the oil temps.

My '84 runs about 175-185 H2O temp in Summer Houston weather w/ A/C on(Ihave a on-off switch direct wired to the cooling fan) . The Oil temp runs 220-230 in the same. I use mobil 1, been drivin' the car since December, and about 7k miles-no problems.

OK now I have to admit I'm confused because I thought that coolant temps of 195 on the highway were normal. I guess I assumed that my oil temps were a little high, not that the coolant temp was too low. What is the normal coolant temp on an L98 at highway speed? I know it runs higher in traffic and will reach mid 220's when the fan kicks on but it pretty steady in the 195 range at 60 MPH. Thanks again.

Like I said, my L98 rarely gets below 200. xrcrx do you still have the original L83 crossfire? That may explain why his is a little lower. If others can chime in too, maybe can figure out what the average everyone else is running. Regardless, I wouldn't worry too much.

Sorry for the confusion. My L83 ran just a bit hotter than now. Since I made the fan switch pro-active the car runs cooler. Temps in the 195-205 range are nothing to be concerned about for an L98 owner. Even 220 - 225 in traffic in the summer isn't uncommon. Today in the Houston heat my car was running 228 oil and 182 H2O W/the fan running while on the freeway. The fans should come on when the A/C is on also.

Alot of the L-98's have factory installed oil coolers. Some on the corvette forum refer to them as heaters. My cooler reduces the oil temp a solid 20 degrees. On the highway, 10-20 degree difference between the coolant and oil temps. Without it, more like 30-40 is common. Although your temps are not excessive, you may want to consider an oil cooler. They are well woth the money, in my opinion.

Mine stays around 230 but it also runs a quart low every other week too. Stupid piston rings are gapped like that on purpose...And I have yet to find out why.

Engine builders often increase the end gaps on the rings purposely. In a high heat situation, rings can grow and the gaps will tighten to the point that they butt. This causes bad chit to happen. Larger end gaps tend to use more oil, but will not allow for the butting that can pop the motor. Most small blocks I assemble use a qt every 1k or less. I also increase the clearance of the valve guides and use teflon seals. This allows for a bit mor oil on the guide. It is better than "sticking" a valve.

THANKS!! Now I know why.

good info, i've been running redline waterwetter, so my engine temps are now lower, especially water temps, oil is about the same :thumbright: