Hello guys,
I just finished upgrading the my stock 2015 Fiesta ST Intercooler to the Depo Intercooler. However, when testing it (in 68 degree night time California weather), I noticed my oil temperatures rising fast. In a short 10 minute drive my oil temperature went from 122 to 200 just driving casually.
With the stock Intercooler, I would be in the 160 - 170 range and not rise higher. Now, every time I hit the throttle, the temperature rises quick.
Does anyone know what could be happening? Is the Intercooler moving too much hot air into the radiator?
Thank you
Honesty, I would avoid looking at the oil temps. It is an educated guess at best. They are an inferred value that I just don't trust that in any performance oriented situation. If you want to know the real oil temp, you can figure out how to add an NPT port somewhere and put a gauge inside the car.
However, adding that intercooler did create an air restriction for the radiator. The oil in this platform is cooled by an water/oil liquid cooler on the stock cooling loop, it is actually a pretty decent setup IF you can keep you coolant temperature low. The hot coolant helps the oil heat up faster to warm up and cools it off when it is too hot. The reason Ford put colling system in is really just because the turbocharger is primarily oil cooled. While, yes, it does have water ports, these aren't used much for cooling. They are a trick to keep the turbo from cooking the oil in the turbocharger if you turn off the car after a 1/4 pull or very spirited driving. Turbos without water ports are known to coke up with burnt oil if not treated wel.
This means that you probably aren't going to have oil temps too hot as long as your coolant temperatures stay
below what water normally boils at; 212F (100 C) is a great point where good coolant temps should be below. Water can really pull a lot of heat out of the oil. However, if you coolant temps were in the 220-240 F range constantly, you would probably be slowly cooking your oil. When you get to the 245 F coolant, the engine is overheating and goes into limp mode. The coolant degrades a bit and needs to be replaced after you overheat.
Mishimoto recommended to first replace the radiator to reduce oil temps (since the coolant loop is doing double duty of handing both oil and water temps). As long as your coolant temps stay below...say 212 F on the street and track, I don't see a reason to worry about it. The oil has enough cooling. With a turbo swap and a radiator, I always see temperatures in the 190F to 200F range no matter what I am doing. So, I just know that my oil will always be OK.
I am also running oil in the thicker 0W-30/5W-30 range synthetic oil right now for the street, and I am considering something in the 0W-40/5W-40 range for multiple 20 minute track sessions. It is also a humid swamp here, so I'm not really worried about colder subzero startups like those poor bastards further north. I run summer tires all year round.
