Dropping oil prior to change - hot or cold ?

[bkreigsr]

In the latest blurb from Blackstone - they recommend dropping the oil cold - without warming it up.

I've always warmed it up to operating temp prior to dropping, theorizing that all the dirty bits will be re-introduced into the warm oil, and present a representative sample of all the oil in the crankcase.

Blackstone recommends a cold drop, theorizing (I guess) that the dirty bits have settled to the bottom of the crankcase and will be incorporated as the cold oil flows over / around it.

I'm about to change the oil in my 912E today, and am wondering if I should change my 60-year tradition of a warm-up prior to dropping.

What sez the brain trust of oil experts on the board?

Thanks in advance.

Bill K

[Mark Salvetti]

I think one advantage of a hot change is the oil flowing out has a higher velocity and more likely to sweep out any dirty bits at the bottom of the tank/crankcase.

Probably doesn't really matter, especially with oil changes in the summer.

Mark

[PeteKz]

Eh. The sump plate is at the bottom of the case, so everything ends up around it. If you really want to be anal about it, you can remove the strainer screen and sweep your finger around as far as you can reach to get any stuff around the strainer. You wouldn't want to do that with hot engine parts.

I need to change my oil soon too. Let's see, hot or cold...

[proporsche]

well, Allways not hot but warm.....so you do not burn yourself....

Ivan

[2.7RS]

I have wonder about the same for years.

My answer is I have a good oil filter regardless of cold and hot the filter should be capturing everything as oil flows through it.

And hot oil it's just too hot, I don't want to get burn.

So I change it cold......

[theiceman]

okay i have the answer.... okay but not really... whenever oil is hot i get way more out .. and it happened again this weekend.

I got stuck in bumper to bumper traffic this weekend and temp hit 200F , which is very rare for me.
As soon as I got it in the garage i grabbed my pans and started draining .. the reason i do this is the stats are wide open , so nothing is getting trapped in the cooler.
When i refilled i put in 11.7 Litres.
There is absolutely no way in hell I am getting that much out with stats closed trapping oil in the cooler .. Even if it is just " warm" stats will begin to close when you park it and start to get ready for oil change.. do it hot hot hot is my motto. But as Ivan states, be careful and wear thick insulated ringer gloves or something similar.

I was supposed to change it at 290 k .. but took advantage of the opportunity ...

ended up changing at 289,911.. which i thought was a good sign .. lol ..

[KNS]

Are you taking about the fender mounted cooler up front? If so how are you getting oil out of the cooler even with the T stat open? Oil won’t flow “uphill” around the front wheel arch.

[gamin]

Elephant oil lines to the front have a schrader valve which allows you to blow the oil out of the lines into the oil tank. Works great.

[shadowjack1]

I do both as it were. When its hot I drain the oil and let it drain overnight. I even drain the "S" hose.
I get as much oil out as I can.

[Schulisco]

Warm/hot oil draining is definitely preferable! Reason: The dirt and carbon residues remain dissolved in the oil and get flooded as long as the oil is hot. The more the oil cools down, the more these heavier particles sink back down to the bottom and areas where they cannot be flushed out.

For those who do not want burn their fingers probably this could be a smart solution:
https://www.stahlbus.com/products/en/oil-drain-valve/index.php
US Shop:
https://www.stahlbus-us.com/oil-drain-valve/

Thomas

[GH85Carrera]

I have done both hot and stone cold oil changes. over the 196,000 miles on my 911.

It is hard to argue with Blackstone. They are the testing lab most people use.

I have a drain valve on my oil tank.



It is nice to slow the massive rush of oil when the oil is hot to avoid the splashing. I have a metal "zip tie" strap on it to make 100% sure it is not opened without a pair of cutters cut the strap off.

And draining the oil from the lines and the front cooler seem overkill to me. With all that oil, and it never gets black, it is just not worth the effort.

[pmax]

Don't.

200F oil can send you to the ER as it gushes out in a torrent.

Let it cool to a safe temp.

[eastbay]

Hot or cold? depends on ambient!

[porsche930dude]

Iv done it cold a few times and boy it sure is nicer. You dont get burnt and half the oil is in the case so your pan doesnt get super full when draining the tank. Its good to hear the blackstone theory because i was thinking the same thing. Also there is less oil coating all the engine parts its all settled down. It probably doesnt amount to much though. Doubt it makes much difference either way.

[theiceman]

Originally Posted by KNS

Are you taking about the fender mounted cooler up front? If so how are you getting oil out of the cooler even with the T stat open? Oil won’t flow “uphill” around the front wheel arch.

closed T stat will leave the lines to and from the cooler full as there is no vent. Opening the stat will allow lines to drain and likely syphon out oil in cooler loop, but even if is doesnt its way more than stat being closed.