Curious too what you guys with coolers are running for oil filters? Some may be better than others at preventing drainback.

From when I talked to Mocal about this ages ago, they said the paths to the oil cooler are actually permanently open. Nothing ever closes over those paths. The thermostatic valve controls the flow passageway that bypasses the cooler, closing it off as temps rise. So yes, it will definitely drain back if gravity allows (bottom fittings).

Oil coolers plumb in before the filter (pump->sandwich plate->cooler->sandwich plate->oil filter->engine). The cooler will still drain back even if the filter has a checkvalve.

Ah, that's right!

had the nismo oil cooler installed. big *** 34 row setrab, anyway i was investigating the annoying *** whine noise all the coolers seem to make and decided to simply check the oil to make sure it wasnt leaking after about a week. well i pulled out the dipstick and cleaned it off, dipped, and it was over the "full" mark by almost a quarter inch. now........ i know overfilling the oil is bad, but with that giant oil cooler IS IT ACTUALLY OVERFILLED or is the dipstick measurement now null and void due to the cooler? i dont know how to get the proper amount in the car with the cooler on it. oh, and the car was still hot when i took the measurement..... dont know if that matters. also, what happens if you overfill the oil? its been running like this as a daily driver for over a week before i noticed.

Is your cooler mounted upright or facing down? Being facing down it can alter the measurements from what I read on other threads here. But there's a thread here on how to get it correct with facing down methods. It's best to check when cold or cooler. I believe it can be off by 5% when hotter. But don't take my word on this.

Mine is up and have had no issues getting the proper measurement. When I first installed mine I filled the cooler up then installed the lines. Then I continued to fill the engine. Which I knew the lines would account for a little bit more oil. So I let the car run a mintute, turned it off and topped off the rest. But I check it often that first two days. I always chech it before I drive anywhere everyday I drive it.

Over filling can ruin the seals but sure your fine for it would take some time before this happens.

/\ that's why your oil measured to high on the dipstick.

If u mean the fittings are on the bottom of the core, then yes it's facing "down"