I have a Alfa Romeo 159 from 2007 with 1.8 GM petrol engine(F18D4 version). For more than 4 months the oil temperature raises more then normal when I go over 74 mph and gets to 130-140 C degrees (266 Fahrenheit ) and keeps getting to 140 (284 Fahrenheit ) if I keep accelerating. When I drive the car under 74 mph the oil temperature is normal.
The normal operating temperature is 110 C degrees (230 Fahrenheit ) and in the past if I drove the car with 111 mph and loaded with people and luggage the oil never reached more then 248 Fahrenheit .
The water temperature is always at 90 C degrees(194 degrees Fahrenheit ) like the producer says, the oil and filters are changed according to the producer specifications.
I went to a mechanic and he said to change the oil temperature sensor but he didn't even checked it. :banghead:
In a road car engine oil needs to be at least 220 degrees F to burn off all the deposits and accumulated water vapor. For every pound of fuel burned in an engine, the combustion process also generates a pound of water! If engine sump temperatures rarely exceed 212 degrees (water’s boiling point), the water will mix with sulfur (another combustion by-product) and create acids that can eventually damage bearings.
As for ultimate power potential, the general consensus among most is that hot oil and cool water make more power in most engines. Cold engine oil causes excessive frictional drag on the bearings and cylinder walls. A quality conventional motor oil will tolerate oil sump temperatures of up to 250 degrees, but starts breaking down over 275 degrees. The traditional approach is to try to hold oil temperatures between 230 and 260 degrees. Even on a short-duration trips I would not want to routinely see under-200-degree oil temps.
A full-synthetic oil will withstand sump temperatures in excess of 300 degrees, and for hard-core professional racing, some oval-track race teams are experimenting with ultra-thin, specially formulated, race-only synthetics operating at 350 degrees or even higher.
(Copied from a post I put on another car site)
Also remember that a high-end engine is built as a total combination. Piston-to-wall clearances, piston ring end-gaps, and bearing clearances are specifically tailored to match the engine oil’s characteristics and intended operating temperature.
Thanks for the info it really helps to understand better.
I know that the flashpoint of 5w40 is 439 degrees and on my car didnt reach the gauge flashpoint.
But for me it's hard to understand how the water temp is normal and the oil goes up, even if I changed the oil.
If the sensor is not the problem.....that means the engine has a big wear?:rotate:
Glad you resolved you oil temperature problems. However, can you give me a view on how well you are taking to the car.
My little GT 1.9 has been brilliant over the years but is really at the end of it’s life. Mechanically still great, but tin - worm has done its worst, particularly along the sills.
My Q4 is still being worked on, but I have seen a N/A 159 with pretty low mileage which I am tempted to buy.
Needless to say, I wouldn’t be buying it as a “performance car”, just a reliable (I hope), run around. It would get me over my problem as I am reluctant to get the GTV out - low mileage, but increasingly impractical at our age.
The oil can't easily get above 120C.. since the heat would transfer into the (water) cooling system, until the cooling fan/thermostat did their thing. If it was really climbing, you would see the coolant temperature rise to 92C and the fan would kick in.
Another clue is that if you're running downhill, you can lift the throttle and the oil temperature should fall. On a trailing throttle, it can't still increase in temperature, even if the engine is on fire..
A blocked cooler won't help. If you get the chance, remove the nearside wheel-arch liner and give the cooler a clean, using a fairly stiff brush to get the mud, cow-**** etc. out. You can also inspect the connectors (these can rust and lose oil). There is a thermostat on the cooler that *could* be jammed closed... and that might affect oil temperature (since the cooler isn't getting any hot oil to cool down) but this is very rare, compared to a sender fault.
Nope....lol...but I can see what you are saying. I did say I copied it from a post on another site, which I did.....I never actually wrote it and never meant to imply I did!. Was quicker to copy and paste (since it said exactly what I wanted to say (near enough!) it rather than use my own dodgy prose!
Ah, I see. I did wonder with your usual writing style!
An informative piece nevertheless. :thumbs:
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