So I’ve had my RCF for 8 months and with no issues until today. I’ve driven it in 110 degree heat and the oil temp never moved up from center whereas today it’s moving down once fully warm.

I’m driving today for about 25 minutes and the oil is fully up to temp according to my gauge. After going another mile or so the gauge reflected 1-2 bar drop and subsequently rose once I was idling at a stoplight. It’s about 55 today and noticed the same behavior yesterday but thought I was seeing things.

I’m thinking thermostat or something with the oil cooler. Car has no codes, no CEL and drives perfectly fine. I’m open to any suggestions and I thank you in advance.

 

The temperatures are much cooler so it might have been over compensated (with the oil cooler) and dropped a bar or two. Sounds normal to me.

 

What’s your coolant level like?

 

I know that there is a mechanical thermostat (close to the same way that a coolant thermostat works) that allows oil to flow into the auxiliary air to oil cooler on the driver side of the car. Before that opens, the coolant is pushed through a donut shaped oil cooler that is a water-to-oil cooler. If anything its probable that the air to oil cooler had it's thermostat open and hence while moving, the temperatures were lower when moving and higher when stopped. Not sure exactly if thats the case here though. Considering the air was cooler today that may have something to do with it. I haven't seen any cases of the oil thermostat going, yet the car is new and stuff. If you wish to see an image for yourself, I have one from a parts website

Part number 15660 is the thermostat housing and part number 15701D is the air-to-oil cooler assembly. I'm assuming this phenomenon is normal, maybe I'm wrong.

 

It’s fine and if it were low, wouldn’t the car overheat instead of affecting oil temp?

 

How many miles on the car?

if it’s an older car just change the thermostat and only use oem there are likely about $40 3 10mm bolts and it’s an easy job. May have to ad a little coolant. Anytime I’ve had temp changes that are odd I’ve changed the thermostat and it resolved things. They can stick and cause wonky issues

 

Actually, if the coolant level were low, it would generally keep both the water and oil temps up above normal, while moving or stopped. I think that if the coolant thermostat was stuck open or closed, the car would overheat if stuck closed and if stuck open it would take literal ages to warm up. If the oil thermostat was stuck open, the oil temps would also take ages to warm up, of which I don't believe is the case.

I personally believe this isn't really an issue, as the car isn't overheating or taking long to warm up. The air temperatures are down, so I would assume its just the air-to-oil cooler doing its thing.

 

When I had the valley plate leak on my ISF my coolant level was always below the full line. I would have intermittent cases where my temp bar was one bar lower than normal.

 

In cooler ambient temps while just cruising on on the highway, sometimes my oil temp will be a tick below the middle. I believe that is normal.

 

Makes sense, thanks for your input here!

 

On cold days I get the oil temp to dip a bit off center from time to time. Plus, its takes forever to get the oil warm.

 

Just got my RCF, and I have this issue as well (not really sure if it's an issue tbh lol). My car's oil temp gauge seems to always be a tick below center unless I am pushing the car or driving aggressively. Could be due to the cooler weather here in Texas this week (it's been in the 50s and high 40s). My only reservation or worry about this "issue" is if it's still ok to floor it or accelerate to redline when the oil is just one tick below the center. It pretty much does not warm up to the center unless it is driven in this manner. Do y'all think it's ok to still push the car to redline when the oil temp is a tick below center or is that abusive to the engine? Please let me know what you all think.

 

Your tach has a graduated redline that goes up as the temps get to an acceptable range. I don't believe being a few ticks below the center affects that (full redline occurs somewhere around when water is full temp and oil is partially up to temp). Your transmission will also shift based on it's current temperature.

 

Yes, you are correct. The oil temperature being one or two ticks below the middle line isn't a problem, generally that means the air-to-oil cooler is just doing its job. Colder air temperatures mean cooler oil, since oil flows through an auxiliary cooler, cooled by moving air. Generally speaking, the redline will fully open up when the water temperatures are about 2 ticks below the middle, I believe it is the same for oil temps too. The redline should remain at 7,300 even if the oil is one or two ticks below the middle temperature. Basically, in a nutshell, its totally fine. Having cooler oil also helps cool the engine, which will make the engine last longer. Cooler oil is almost always better than overheating oil (the RC F does a super good job with cooling itself). I believe this 'issue' if you want to call it that, is just the oil cooler doing its thing.

 

Thanks for the clarifications guys!