I discovered how to easily drain the oil cooler! (on my 91' at least)
 

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.

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

Interesting but I would be concerned draining all the oil out of the cooler. In my mind you risk a possible dry start as it may take a few seconds after startup to replenish the oil in the cooler.
Rich

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

Thanks for that! I have new oil cooler lines that I need to install to stop the dread oil seepage where the metal fitting is crimped to the hose. I was wondering how I would pull of the cooler inlet/outlet and not get oil all over the place. Now I know!

I tend to think the few seconds to refill the cooler with oil on re-start is not a concern. Everything internal stays coated with oil. Some larger oil filters can hold a half quart, and you cannot always pre-fill them when you change your oil because of the way some are positioned, like on a ZR-1!

Thanks for posting that info.

John

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

Easy enough to prime without starting. Cool! I'll have to look for that. Changing 80% of the oil has always bugged me.

- Jeff

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

Rich I would agree with a fresh motor but would there not be enough oil to still be coated all over the surface? I agree it maybe a risk.

ON another note what size fikses are you running? 18s?

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

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.

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

When draining coolant for a flush, I've always held a Shop-Vac to different openings to try to pull the juice through to some place it would drain.

Seems to help a little; I hear the leftovers sloshing around when I do, and some additional DOES drain out...

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

I serviced the engine to nine quarts, the FSM says the engine requires about 10.5 with filter change and cooler drain, I started the car and the oil pressure came up at the same time period (actually a little faster, used Amsoil 10W-30 instead of 5W-30). Drove it around the block and I will check it tomorrow. Weird, but I believe I had less chain chatter using the 10W-30, or it was my imagination. I didn't like doing an oil change and the oil immediately turns dark when it mixes with those last two quarts.

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

The cooler uses the same plug as the rear differential drill/drain kit that CorvetteCentral has. I bet it could be screwed in too far and be stuck inside the cooler, I was thinking of replacing it with a bolt instead, maybe next oil change. As far as not being a service port, the FSM gives oil refill quantities if you drain the block, block and filter, block and oil cooler, block and cooler and filter, and engine overhaul.

The big thing I didn't like is that over time the acids and whatnot that break down an oils additives, it is nice to get as much of the old out as possible. Going over the Amsoil site and reading their monthly newsletter is really informative info for the gearhead.

However, the FSM doesn't really explain what is involved in a 'routine' oil change, so I guess we will all have to make up our own minds if you want to mess with the cooler.

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

I had my oil cooler out when I swapped in my new motor and it did not have any kind of plug like the OP mentions.

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

Cooler by application part #'s is '90 - '93 and '94 & '95 a different part #.

'90 - '93 = 14104653

'94 & '95 = 10219643

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

Seems kinda' strange that pressure would come up faster, after a change, with the cooler drained too... :confused: ... especially if air would only compress, before pushing through.

Dave; is tube configuration different for the 2 different coolers?

Summary of Oil Cooler Drain Plug
 

Great Info........:thumbsup:

Excellent Conventional Wisdom :handshak:
I would expect that the flow through the Oil Cooler is of such significant velocity/pressure that contamination deposits would not STALL in the bottom of the Oil Cooler. Such accumulation of contamination deposits could over time close off the oil cooler. My thinking is that such deposits would be cleared by force (oil pressure and hydrodynamic cleaning) within the oil cooler narrow passageways. I am also thinking the Oil Cooler Flow is Filtered just after the Oil FIlter (just thinking).
http://i287.photobucket.com/albums/l...ps4cacf14a.jpg

I am assuming that this oil goes to the Oil Cooler after the oil temperature has opened the oil temp thermostat directly from the Oil Filter. I would assume that this oil is newly filtered oil having passed through the Oil Filter Adapter Housing.

I LIKE Part Numbers :thumbsup:

Great Additional Information
Meaning that Oil Cooler Part # 10219643 (94' and 95') does not have the Drain Plug.
This Oil Cooler information is for a your 1994 I am assuming :cheers:

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

If I recall correctly, the oil cooler is not in the full flow path until the oil temp thermostat in the oil filter adapter opens. Prior to opening, the oil flow to/through the oil cooler is minimal, so that when the oil t-stat does open, the cooler is fully charged.

That is why you will not see any abnormal pressure lag after an oil change with an empty oil cooler, as mentioned by the OP.

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

Hi Jerry, That is exactly what I was thinking as I read this post. In my opinion, you are 100% right on. George

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

Oil THERMOSTAT???

Is this a service-able item, that warrants a maintenance eye?

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

I agree with Jerry that the oiler cooler is only in the flow path when the oil temp thermostat begins to open. As I mentioned above my 94 model year oil cooler did not have any kind of a drain fitting. For flushing the cooler I filled it with clean solvent through the inlet and return ports at o-ring flange connection then shaked the cooler back and forth to work the solvent through the tubes then cleared it with compressed air. Initially I was surprised how many times I had to repeat the process until the solvent came out clear. Appears to me that over time and miles thickened oil and the usual oil born sediments accumulate in the bottom cooler header tube. After thinking about it I do not find this unusual. If this were an oil cooler from a industrial engine like we see at work no attempt would made to clean it. Instead it would be replaced with a new cooler.

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

Jerry - That's what I recall Tyler mentioning also and I didn't comment BUT had this question. If you drain 60 oz of oil and add 60 oz to the conventional fill the crankcase is 60 oz overfull until the t'stat opens which I thought Tyler mentioned as "seldom"? The 60 oz "over-fill" I think needs to be considered here as "compromised" and possibly "catastrophic". I used a 60 oz number assuming that was what might be measured in the draining not anticipating the 64 oz capacity as "gospel".

So your only option would be to do the conventional fill and then watch for a "low level" on the dip stick? I just can get past the "conventional" wisdom that has prevailed for years.

Am I missing something?

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

http://www.anchoredbygrace.com/smileys/lurk.gif




and this is good info too...

PW - you think it was really the chunky stuff? Or just the old oil?

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

Another point, the oiler cooler by itself does not account for all the oil that cannot be drained. The oil cooler volume on my 94 is around 1.4 quarts.

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

No, I don't think so. For a conventional oil change, sans oil cooler purge/drain and assuming the change started with a full oil level; I don't go to the trouble of actually measuring the amount of drained and replacing with the sme amount. There is so much oil capacity in the LT5 that I simply re-fill with 9 qts, then go drive, park overnight & top it off the next day.

Over the years, there have been several reports of engine damage associated with overfill, most of which were changes performed by dealer or quik-lube type facilities. They simply drained the oil, looked up the capacity and refilled with the full capacity amount.

I agree with you. The only exception is the very small volume of oil that bypasses the oil temp thermostat. The 60 oz would eventually find it's way into the oil cooler, so I don't believe it would be necessary for the oil temp thermostat to actually open. I also concur with "seldom," regarding the open t-stat event unless the car is being tracked.

Wish I knew an empirical value for the oil flow to the cooler while the t-stat is closed. Good question to ask Graham next time I get the chance to talk to him.

In the Service Manual there is a oil filter adapter cross section showing the internal config and oil flow, but its not easy to follow. I might try to see if I can Photoshop it with red for full flow with t-stat closed, and blue for t-stat open flow.

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

I have had an engine on the stand for 3 or 4 years, oil drained & pan plug removed. It's still dripping oil. There's a lot of residual oil in the LT5, which is apart from the oil cooler volume.

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

Correct. On my 91' the engine still has 1 qt in it which can only be replaced with an overhaul, according to the FSM. So in my case instead of three quarts I have 1 qt that doesn't get changed.

Re: I discovered how to easily drain the oil cooler! (on my 91' at least)
 

It is likely because I followed the FSM and and installed 10w-30 instead of 5w30, not how the oil was changed.