yea it's necessary. maximize cooling because through the cooler is the only path

 

My car originally had one oil cooler unducted. It had a FMIC and upright un-ducted radiator. I couldn't even drive the car around here in CO. I had to stop 4 times going up long mountain climbs to 10,000FT with this set up going home from CA (CA purchased car). I put in a thermostat, still had problems. put in ducting for the radiator and dual oil coolers and my temps have been good since. I went to a ducted v-mount set up and when I drive the car hard the temps stay stable. it only creeps up when I am not moving till the fan activates and holds steady.

In my opinion dual oil coolers are necessary, especially at higher elevations, if you only have 1 port for the cooler I would duct it well and duct the radiator to ensure all air goes through the heat exchangers.

 

Are ducts necessary is based on the air that bypasses the oil coolers. I have a '99 bumper with unducted 25 row Setrabs and the oil temps are TOO LOW for street driving (like not getting over 170). I am using aftermarket mounts which places the coolers close to the openings so little air escapes other than the inboard side. The stock mount may be different. Mock it up and see how it looks, with and w/o the stock ducts. You may be able to fab a surround from the stock ducts to the '99 bumper opening. If all that is far off, there's the RHD option you mentioned. In the end, dual unducted stock coolers on a '99 bumper may be about the same as a single ducted cooler on a USDM bumper, which should be ok if you don't track it. Only way to really tell is to get an oil temp gauge.

 

Objective evidence indicates that only ONE oil cooler is sufficient. As noted several times, the automatic equipped cars use only one oil cooler. Assuming that this cooler is the same size, i.e. has no more cooling capacity than either one of the manual transmission-equipped cars, then...there you go.
As also noted, any extra stress put on the oil cooling system, e.g. racing, stop and go traffic, performance mods, etc...will task the overall system.

 

Yes, highly recommended.

Very interesting. I think for the stock system (with a second thermostat), overcooling may not be such a large concern.

Edit:
CCE has a neat washer/overflow tank for those trying to optimize oil cooling by removing airway obstructions behind the cooler.
http://www.cce-web.com/pleasure.html


People also may cut/drill some holes in the stock fender liners to give air another escape path.

 

So... after installing my dual oil coolers, I noticed an increase in oil pressure.
Not so much at idle, but once I get on the gas, above say 2500 rpm, the oil pressure shoots up to 800kpa (116psi) and stays there til I get off the gas. Does that sound right?? Maybe I have some minor kink in the hoses? Any ideas? (At least it doesn't go much above 800kpa)

To the post quoted -- I always assumed there were no holes in the fender liner for a reason, and assumed the reason to be that the hot air was ducted up and over the wheel, and out the side vent behind the front wheel... at least that's what I can gather from my observation -- I wonder why they didn't just add holes or vents immediately behind the cooler(s), though.
Any ideas?
(My old nissan 180sx had vents in the fender liner for hot air after the stock side mount intercooler.)

I just installed the SBG dual 19 row setrabs (didn't want the clearance issues of the 25 rows) and I'm a bit disappointed at the amount of space between the framerail and the oil cooler. The cooler is right up against the inside edge of the bumper skin, but is spaced 2.5" away from the framerail! One might argue it's for air to the brakes, but I don't really buy that. Any ideas why this is?