BriK

iTrader: (11)

For the longest time, my oil temp on my stock MR gauge wouldn't go any higher than 70C. Recently, the oil temp easily goes above 70C and can hit 90C in normal street driving.

I know 90C for oil temp isn't terrible, but I'm more concerned that it never went above 70 and now it does.

Situation and symptoms:
- oil temp goes higher than it did before, but not dangerously high-- never gone over 90C on stock MR gauge
- temp rises slowly, doesn't instantly shoot up
- temp goes up more quickly above 3K RPM's, no matter if I hit boost or stay in vacuum
- staying under 3K RPM's on the freeway causes the temp to gradually drop
- highly dependent on outside temp-- higher ambient temp= higher oil temp
- when in a car wash, the oil temp drops dramatically when the drying fans are at the front of the car
- water temp gauge reads normal (stock gauge) and car heats up the same as always (not too fast or slow)
- radiator fans kick on normally and run fine
- no boost leaks
- no coolant leaks
- no oil leaks
- no coolant in oil
- no smoke from the exhaust-- white or black
- voltage to the oil temp sensor is fine
- same downpipe the whole time, same LICP whole time, etc.

What I've done:
- thicker oil didn't make any progress, only made oil temp go up more easily (as expected for a stock motor)
- replaced thermostat housing, coolant temp sensor and fan switch
- thermostat looked fine but I didn't boil it to check. I attempted a new thermostat but was sent the wrong one so I had to put the same old one back in

What I plan on trying:
- New thermostat with the theory that the t-stat isn't fully operating, causing higher engine temps, therefore causing higher oil temps-- temps so high the oil cooler alone can't remedy them.
- Coolant flush
- Been searching hard for an OEM oil cooler thermostat but can only find HKS low temp option (don't want) or Tomei eliminator (also don't want)
- New oil temp sensor, just cuz

Any other theories I should investigate? Anyone have the part number for just the oil cooler thermostat? Would like to avoid a whole new oil cooler if I can.

TommiM

iTrader: (19)

You said going with thicker oil increased oil temps, then go back to the thinner stuff you were using.
90 deg celcius is roughly like 194 deg F. The oem oil cooler thermostat doesnt even open till 180 deg iirc. I dont think you have anything wrong going on with your system. Maybe the air scoop in front of your oil cooler came loose or you got debris in between the fins of the oil cooler. That can cause a slight increase in temps.

FWIW oil performs best at certain temp ranges. Colder doesnt always mean better.

cfdfireman1

iTrader: (11)

Relax it's called summer. It's been over 100 in Chicago the last 4 days what's the ambient you're seeing? Let us know when the oil hits 250.

Spirit evo 8 MR

i agree, hot weather is mostly the cause of it, mine does the same too, on highway temp is little lower, but come to the stop and watch the gauge go what about ur coolant gauge is it good?

BriK

iTrader: (11)

I'll look at the oil cooler duct-- didnt think of that.

I went back to thinner oil less than a week after trying the thicker stuff.

As I said, it's the difference in behavior, not exactly the behavior itself, which has me wondering.

No other Evo I know of goes over 70C for oil temp unless being pushed hard. Mine does it with ease. It's not a cause of major concern but I'd prefer to fix it now before it spiderwebs into something more.

Chef-j

iTrader: (16)

Thicker oil increase temp? Can i ask what grade you ran?

cfdfireman1

iTrader: (11)

BriK seriously?
So you understand I'll make this post in "centigrade" you don't even burn the H2O out of the oil till you hit 100C, what the hell are you worried about?

barneyb

The oil cooler is perfectly situated to collect bugs. I have to clean mine out every fall.

BriK

iTrader: (11)

As mentioned on multiple occasions, the difference in behavior, not the temp itself.

Logic dictates if the behavior is different, something has changed to cause that. I'm trying to track down the change.

Mmmmmkay?

BriK

iTrader: (11)

10W40. Switched back to 10W30 in less than a week.

This thread explains it best:
https://www.evolutionm.net/forums/ev...40-380whp.html

cfdfireman1

iTrader: (11)

How long have you owned the car? Every single thing you have mentioned is perfectly normal, stop scratching where it doesn't itch.

see post #4

BriK

iTrader: (11)

I love how people are congratulated for meticulous maintenance when selling a car, and criticized for it while owning the car.

Thanks for the non-help, cfdfireman1.

TommiM

iTrader: (19)

I assume your oil level is within spec? Im sure you checked it but you didnt mention it anywhere so Im just throwing this out there. Have you checked your spark plug condition and gap? A slight increase in cylnder temps might increase oil temps as its going through the engine. Anything that can change ignitin timing can increase cyl temps, maybe octane level in your fuel changed

Just a few other thoughts that might cause your symptom. That little increase in your temps is nothing to be concerned about. We thank you for taking care of your evo, but there is a fine line between caring for your car and being hypochondriac about it. Your evo is fine, go drive it and enjoy it

todd6027

iTrader: (10)

where is the oil temp sensor ?? 70 deg temp doesnt sound right your coolant temps are around 76/80 deg and id expect the oil temp to be a few deg higher

Berts24

iTrader: (3)

I've noticed my temps being high when using the A/C it makes sense because I'm putting more of a load on the engine making it run hotter