Higher ECT Temp on 5w 30 oil

Si Is Life

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Hi guys! I just changed to a 5w 30 Penzoil oil and i noticed my ect was higher than the 0w 20 oem honda oil my temp when idling at 5w 30 is at 191 while on the oem honda oil its only 179 as soon as i stop the ECT will easily climbed to 190 in my 5w 30 oil now but in the oem one it will take atleast 5 mins or more to reach 190 while stopped im FBO running E35 blend 2020 Civic Si Thanks!
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There are tons of oil threads on here, but my personal opinion is you should run factory spec. Unless you were heavily built with an upgraded turbo making 500 wheel and the turbo required heavier spec oil, then maybe I’d consider it.
 

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27Won recommends using 5W30 if you have flex fuel, according to one of their YouTube videos. I use 5W30 in my Si without issues
 

fabrizzio71

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The reason i changed to a 5w 30 is because of the ethanol thinning out the 0w 20 oil
I suppose if you are getting a lot of gas in the oil this could be an issue, I personally don't think oil dilution is a big deal at least not on my car with my oil change intervals (5,000 miles). But, excessive heat is something I would be concerned with. Also, it seems the 27Won W1 has a high failure rate seemingly due to excessive heat-I wonder if there is a correlation with oil weight?
 


amirza786

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Oil viscosity debates like political debates can get quite contentious, so I generally stay out of them, but for what it's worth, in 2018 I had a discussion with an engineer at Mobile oil and a technical support person at Amsoil (separate email discussions), and both told me generally the same thing...using a thicker than recommended viscosity oil can cause issues with valve timing due tighter valve tolerances in modern engines. They also mentioned higher oil pressure, which can cause additional heat buildup.

The above being said, I doubt this would affect your ECT temp. It is getting warmer now, and not sure if you are in SoCal or NorCal, but on Sunday I was in SoCal and it was in the upper 80's, and when I got to NorCal later that afternoon it was also in the upper 80's in San Jose. Today the forecast here is 78 F, so that may be the higher ECT you are seeing
 
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Si Is Life

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Oil viscosity debates like political debates can get quite contentious, so I generally stay out of them, but for what it's worth, in 2018 I had a discussion with an engineer at Mobile oil and a technical support person at Amsoil (separate email discussions), and both told me generally the same thing...using a thicker than recommended viscosity oil can cause issues with valve timing due tighter valve tolerances in modern engines. They also mentioned higher oil pressure, which can cause additional heat buildup.

The above being said, I doubt this would affect your ECT temp. It is getting warmer now, and not sure if you are in SoCal or NorCal, but on Sunday I was in SoCal and it was in the upper 80's, and when I got to NorCal later that afternoon it was also in the upper 80's in San Jose. Today the forecast here is 78 F, so that may be the higher ECT you are seeing
The ECT jump i seen was before and after the change oil it was a same day same temperature thats why im wondering why my ECT is suddenly on the high side the only thing i did was change the oil to 5w 30 that day.
 

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The ECT jump i seen was before and after the change oil it was a same day same temperature thats why im wondering why my ECT is suddenly on the high side the only thing i did was change the oil to 5w 30 that day.
They did say (both Mobile 1 and Amsoil support) that higher viscosity can cause higher oil pressures which would cause additional heat build up, but I didn't think that would affect ECT. The only way to know for sure is to go back to 0W20 and see if the ECT goes back to 179. Although I don't think 190 F is a big concern
 
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Si Is Life

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They did say (both Mobile 1 and Amsoil support) that higher viscosity can cause higher oil pressures which would cause additional heat build up, but I didn't think that would affect ECT. The only way to know for sure is to go back to 0W20 and see if the ECT goes back to 179. Although I don't think 190 F is a big concern
Yeah maybe u are right i just got paranoid seeing 190 i just did a search and a lot of them says they are at 185-190ect range
 


ebatr24

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For what it's worth I ran 5w30 on my Si and didn't really notice a difference in temps, flex fuel FBO as well. I run it on my FK8 now and usually sit around 170 while driving and when I come to a stop it creeps up to 185 if I am sitting in traffic. I do also have an upgraded coolant tank and grill tho, not that they should make much difference.
 

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You aren’t running without AC are you? Maybe due to cooler spring weather? With AC off ECT will run hotter.
 

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What ECT threshold is cause for concern?

I've seen ECT up between 175-200 on some hot days, but my temp gauge on my dash will be right at the middle. Unless that one is showing ECT2?
 

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I'm running 5w-30 too. I haven't noticed an increase in temps at all. I also don't monitor ecu temps too much unless I'm at the track. I'm also in the South Florida heat keep in mind. So, just make sure you're not over analyzing. Rise in temps is ok as long as it's not out of hand and car can't cool itself down.
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