What constitutes "normal operating temperature"
 

We all know of and have heard of the phrase "normal operating temperature" with regard to automotive engines. But what object or substance is this temperature referring to? Oil temperature? Water (coolant) temperature? Engine block temperature?

Re: What constitutes "normal operating temperature"
 

In an ideal world, I think it would be the average cylinder wall temp.

Since that isn't easily measurable, we measure water temp. After all, we use the water to regulate the cylinder wall heat, so they should both be about the same temp after the pass through the block.

In an air cooled engine, oil temp is measured (if anything).

Re: What constitutes "normal operating temperature"
 

Coolant should be up to temperature as should oil. Normal oil temp would be around 200 degrees F. Oil takes a lot longer than the coolant to warm up.

Re: What constitutes "normal operating temperature"
 

Yeah that's what I was reading about in Dr. Haas's oil 101 article on the Ferrari Chat forums. He was talking about normal oil temp around 212 F for normal road driving, but that it could get up as high as 300 F on a race track. And then the coolant temp should stay around 180-190 F, but it heats up faster than the oil.

Somewhere in that article or in the discussion afterwards, it was mentioned that the oil can take as much as 20 minutes to get up to operating temperature (where the oil is at the ideal viscosity to prevent engine wear). Man if that's true, then all of us who commute less than 20 minutes to work every day are in trouble.

I commuted about 8 minutes each way every day for just over 2 years, so I just hope that didn't do a great deal of harm to my engine. Now my commute is right at 20 minutes almost exactly. Engine has 274K miles btw, with no noticeable oil loss in the 3K mile oil change interval.

Re: What constitutes "normal operating temperature"
 

The reason the oil should get up to about 212 is so that any water that may get into it will boil off. For every gallon of gasoline that burns more than a gallon of water is produced. Some of that water gets into the crankcase through blowby past the rings and into the oil. When the water mixes with raw fuel in the oil it creates acids and can form sludge. This is why it is important to have a good PCV system or crankcase evacuation system. People that pull off the PCV system and just put a breather in the valve cover are asking for trouble.

Re: What constitutes "normal operating temperature"
 

Lol, I think that's why my stock 94 Accord just failed inspection. I have a 15 minute drive to school and a 5 minute tops drive to work. I failed for high CO. I think the constant short trips are really tiring the motor out

Re: What constitutes "normal operating temperature"
 

A worn out engine isn't going to cause high CO. Either your engine is running rich or your catalytic converter is not efficient.

Re: What constitutes "normal operating temperature"
 

I thought that the rings might be losing their seal & burning oil, giving high CO or something. I don't see any reason for it to run rich, other then being old lol. Cat is 1yr old

Re: What constitutes "normal operating temperature"
 

What were the emissions readings? Oil burning does not cause high CO. Do the test the emissions on a dyno in your state?

Re: What constitutes "normal operating temperature"
 

Short trips are one of the things that motor oil producers consider severe duty.They recommend shorter change intervals for short commutes.I consider 200* of water temp and 220* of oil temp normal.

Re: What constitutes "normal operating temperature"
 

All this talk makes me want to get both an oil temp and an oil pressure gauge.

Re: What constitutes "normal operating temperature"
 

jeez, my car never gets up to normal operating temp then.... even my 400+hp turbo car rarely sees oil temps over 200 and even less often for coolant.

my all motor b20 teg does see coolant temps of 200-205 on occasion through the neptune datalog.


i always thought normal op. temp was when the fan started to cycle, and it was intended to represent when the metal in the motor was all heated and expaneded, sealing everything as best as possible

Re: What constitutes "normal operating temperature"
 

Actually the water gets heated faster than the block and other components so it takes several heating/cooling cycles until every thing is up to temp.

Re: What constitutes "normal operating temperature"
 

My CO was .95 and the max is .73. Yes my state does a test with the rollers.I just threw in some Gaurenteed To Pass and NGK G-Powers. Only thing on the motor is a SRI. I didn't think that would cause me to fail, if that's why I'm running rich.