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

[A26B]

Originally Posted by WVZR-1

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?

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.

........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".

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.

[A26B]

Originally Posted by Jagdpanzer

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.

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.

[Blownrunner]

Originally Posted by Jagdpanzer

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.

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.

[Blownrunner]

Originally Posted by Schrade

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

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

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