What is the desired temp split between coolant and oil?

My oil temp was at 179.53 and the coolant temp was at 175.20 when I got home today. i am having some troubles, see "MAP sensor" post or "runability issue" post from earlier today.

Thanks for any ideas or info.

 

Under normal circumstances, oil should not consistently be 15 degree's more than coolant. However, your coolant temp is way too low. It should be at least 190. You probably need a new thermostat.

 

Hey David, agreed. I also have posted under the MAP sensor issue. I haven't gotten a solid response from earlier posts so I figured I would break up the info to draw a bigger "crowd" if you will. Does this seem to suggest a common point issue when combined with the other values I have given in other posts?

 

Low coolant temp might cause a slightly less efficient fuel burn, and thus poorer fuel economy. But I don't think it should cause the problems you are describing.

 

The OP reported temps "when I got home." That is clearly not enough information for you to decide his thermostat isn't working.

We don't know how far he drove nor at what speed. Were the last 3 miles of his trip home at 75MPH or 25MPH? Uphill or down?

I've driven 50 miles on a 65MPH limit highway at an outside temp of +20F, got the water temperature up to 185F, then watched it drop to 175F during three miles of 25MPH driving to my driveway.

As for the temperature split, is the OP reading OBD II data or aftermarket gauges with senders in locations other than the factory senders? If the OP is reading OBDII data, nothing in his post indicates trouble with his thermostat.

 

55miles home, outside temp was around 38deg. last 5 miles was around 45mph and yes, the temps were taken using the Auto Enginuity plugged in to the OBDII port

 

The 15 degree delta is supposed to be applicable only after reaching operating temperature on the coolant/oil/engine.

 

I've driven my fair share in fridgid weather and never seen my temp drop below 188, no matter how slow I was driving. I would say if this is what you are seeing you need to look at YOUR thermostat as well.

 

And I was going to say the same thing, but you beat me to it. You should not fluctuate that much.

 

Mine fluctuates alot too. And I would agree, I need to replace the thermostat. There is no reason it should fluctuate much. Especially below operating temp. I just need to get the time to do the coolant flush. It's finally getting above freezing around here.

 

Except for the fact that I've seen my coolant temperature above 190F in -20F weather. Every stop and think I'm feather-footing the throttle on snow and ice?

I can make my coolant go above 190F anytime by flooring the throttle after the engine's warmed up. I don't need to look at my thermostat.

 

Specifically, the coolant needs to be at least 190F for the delta to apply.

 

So how did your coolant temperature drop to 175 deg. for 3 miles while doing 25 mph at that outside temp? Mine has never dropped below 185 whether doing 25mph or stop and go traffic at 25-35 outside temp.

 

You can maintain or not maintain your truck however you like, I don't particularly care. However, no amount of "feather footing" or slow driving should cause your coolant temps to drop the way you described. It is indicitive of a thermostat that is not operating properly.

 

Your previous post referenced frigid weather. Now, it's +25F - +35F. So, you don't think there's a big difference between -20F and +25- +35F????? That's only 45 to 55 degrees apart.

1. My cooling system is in better condition than yours. Perhaps you need to take a closer look at your cooling system.

Made the same trip today in +59F weather. Coolant reached 198F flooring it from 50 -70 MPH on the highway with oil at 201F. Oil temperature was 194F and water was at 191F in my driveway because I floored it up a 7% grade 1/2 mile from home.

In case you can't read between the lines, I think online diagnosis of any problem is 50% guessing. When it involves driving style, weather, route, etc., it becomes 96% guesswork. If you think a 55F difference in outside temperature is not material, it's 99.98% guessing. I think.