Oil temp during cruise

[Birdseyeview]

I've got 7 hours on my 912 ULS and all the temps and pressures are good during takeoff. However, after 10 minutes at cruise (5000rpm and 70F ambient) the oil temp creeps up to the top of the yellow band (240F). It doesn't seem to go any higher but I have backed off the rpm so it hasn't really had a change to get any higher. When I back off on rpm it comes back down into the middle of the green band and stays there. I'm nervous about what will happen during really hot day ambient conditions. I have an oil cooler and an oil thermostat, both purchased from Kitfox. This cooler wouldn't fit well directly behind the lower cowl inlet hole so I put it in front of the radiator. All the oil temp posts on the forum that I've read so far seem to show that most builders have a problem not getting the oil temp up high enough to boil off any water in the oil and they have put on all kinds of different mechanisms to close off air to the cooler to force it to run hotter. My oil cooler is about 3" in front of the radiator so there is no direct ram air into the oil cooler and I don't have a big NACA duct like on the series 7 lower cowls (not much ram effect to the oil cooler or the radiator).

IMG_8494.jpgIMG_8491 2.jpg

One previous post I read that seemed to make some sense to me theorized that the three openings in the front of the cowl let in a lot of air and the radiator restricts that total air flow out of the engine compartment. My sheet metal around the radiator is close to the lower cowl and so it doesn't let much air bypass the radiator. As a result of this restriction across the radiator, a slight air pressure may be built up in the engine compartment that produces a given air pressure drop across the radiator. This pressure drop allows a given airflow through the radiator and this airflow enables the heat transfer. The oil cooler also needs an air pressure drop across it to enable air flow through it. However, the slight positive pressure in the engine compartment just doesn't allow much if any airflow through it. The low placement of my oil cooler doesn't allow much ram air effect either and the gap between it and the radiator doesn't help the pressure drop across it that is needed to get air flowing through it. It seems like I might have a few options to improve air flow through my oil cooler, as follows:

1) Do nothing and just monitor it and adjust rpm and air speed accordingly to keep the oil temp within the green band. Maybe the oil temp will lower itself as the engine breaks in?
2) I could remove part of the sheet aluminum shroud at the bottom of the radiator and add a shroud to the back of the oil cooler to direct all its exit air out of the engine compartment via the open hole under the radiator
3 I could put some sort of a shroud between the oil cooler exit and the radiator to force more air through the oil cooler. I can't relocate the air cooler as close to the radiator as I would like because there is a radiator support tube in the way.
4) I could attach a shroud to the front of the oil cooler between it and the lower cowl inlet to force more ram air directly into the oil cooler.
5) Do both 3 and 4 above.
6) Close off the existing lower cowl inlet and install a small NACA duct pointing straight into the oil cooler air inlet side to increase the ram air effect.
7) Remove the sheet metal shroud at the bottom of the radiator that conforms closely to the shape of the inside cowl surface. This might let more air flow through the engine compartment in general but it seems the air will flow out this open hole as the path of least resistance and thereby it might negatively impact the radiator's effectiveness.
8) Increase the overall air flow through the engine compartment by creating a lower air pressure zone on the aft side of the radiator and hope that some of that air flow increase goes through the oil cooler. I could accomplish this by adding a downward slanted "spoiler" on the aft edge of the lower cowl to create a lower pressure on the exit side of the radiator. I've seen some builders do this on pictures of their lower cowls. This would be fairly easy to do but I don't need more air flow through the radiator because my CHT's (and equivalent coolant temps) are good as is. The picture below shows a little slope up of the lower cowl exit. This upward slop is going in the wrong direction to create the negative pressure zone I'm seeking in this option. I assume this upward slope in the existing cowl shape is to help stiffen the cowl and isn't designed in to control and restrict the airflow (via inlet to outlet area ratio).

IMG_8492.jpg

Any opinions on what I might try first to help bring my oil temps at cruise down to a more reasonable level? What other options did I miss?