Changing oil...Let it drain overnight ?

[Dynomite]

Originally Posted by Blownrunner

Pull the oil cooler? My 91's oil cooler has an oil drain plug. You guys knew about this, right? If we are preheating oil in the oven...

Originally Posted by RussMcB

I looked in the manual but did not find a reference or picture of the plug. Is it easy to find and access? I'll crawl under my car later tonight and look for it.

For your information......

Originally Posted by Blownrunner

It seems that everyone accept that the oil in the oil cooler does not get changed during a routine oil change. Did you know, according to the FSM, that the oil cooler holds 2 quarts of oil, about 20% of the oil in the engine?

Determined, I figured out how GM solved this problem: The oil cooler has a drain plug that is easily accessible on the passenger side of the car, aft of the center front spoiler, in the center of what appears to be a large grommet with an allen screw in the middle! Mine was covered up by some type of sealant or adhesive, which is easily removed. The grommet is actually the lower right mount that sandwiches the oil cooler/air conditioning condenser assembly in the front cooler assembly housing.

I am sharing this because it seems to be accepted practice that you don't drain the oil cooler at oil change time. I would be astonished if I were the first to discover this, or at least to post it on this forum.

Originally Posted by WVZR-1

I believe the "conventional wisdom" needs to prevail here because the plug the OP mentions isn't meant to be a "service port". I don't know the thread size involved here but for any thing other than maybe it's use to drain the oil for a cooler change seems maybe foolish. Any conventional engine oil drain plug uses a gasket or seal to prevent seepage and I'm quite sure this could only be some sort of an NPT plug and that's not a conventional method used for engine oil service ports.

Originally Posted by RussMcB

Or maybe I'll do a new Cold Start/No Oil test and add a data point to our knowledgebase. :-)

Ya....let us know how that goes