inkatouring

In a recent oil change post there is some discussion about "hot" oil change with the implication -- if not actual assertion -- that you drain more oil after the oil cooler thermostat opens. I'm a noobie with dry sumps, but wonder how that can happen and whether a hot change is really any different?

I assume the oil lines to and from the cooler always have oil in them (it gets pumped through when t-stat is opened and certain stays there statically when it is closed), as do the coolers themselves. Once the t-stat opens, I understand oil comes from the lines and cooler, but oil also goes into the lines and cooler replacing the exiting oil, no? If so, how can the amount of oil in one place really change? The only explanation I can figure is that my assumption on how the the coolers work is somehow incorrect.

Thanks in advance for enlightening me on this....

No HTwo O

I think the bigger advantage doing it "hot" vs. cold, is that the hot oil contains more of the contaminants (since it is all stirred up) that you want to get out, plus it drains faster.

Steve Weiner-Rennsport Systems

The most effective and thorough oil changes are done when the engine is hot and the thermostats are both wide open.

Quadcammer

awesome.


why?

The Brewmeister

^See post No. 2.

NC TRACKRAT

Try this experiment next time you change your oil: With a cold engine, drain the oil from the oil tank in the rt. wheel well. Measure and record the amount of oil drained. Then go about draining the engine sump and complete the job as usual. The next time you change oil, do it with a hot engine, drain the oil tank, measure and record the results as before. When you're done, compare the two figures.

inkatouring

Well, if that is the answer to quadcammer's "why", it still isn't the answer to my question -- i.e., whether you actually remove more oil. Yes, we all know (or at least I do) that a warmer oil "collects" more contaminents than cold/colder. But, are you actually removing more oil when the t-stats open? If so, why?

helmet993

yes

gonzilla

just because.

P-daddy

I'm confused too. The "stat" opens on a hot engine but if engine is off while doing oil change, no oil is being pumped anyways. That means all the oil in the cooler and tubing stays put while you drain, no?

csertich

Thanks guys. This is timely. Recent threads have had me wondering.
chuck

Ed Hughes

Getting more contaminents out is reason enough for me. Seriously, do some of you have to ponder this issue so long?

Rick Lee

I do it piping hot. I even rush to get the car on jackstands. I pull the hard line off the engine too. I like to get as much hot oil as possible out of there. I'll sometimes let it drip for hours before I button her up and refill.

NP993

I have to say, whether I drain 9.4 quarts during an oil change or 9.7 is one of the lesser things I worry about in life...

inkatouring

No one is worrying (well, at least I'm not). No one is advocating cold oil changes (well, at least I'm not).

I just wondered if there was anything to the assertion that you get more out by changing the oil hot and if you did, how it worked (to me, one of the greater things in life to ponder is how things work). But, given the responses here, I'm thinking the answer is no...