Oil Changes - Hot or Cold?

[Joe P.]

Does it matter it the oil is hot or cold when you do an oil change especially if the car has been sitting for six months...

If the car has been sitting and you do an oil change.. then most of the oil has drained to the bottom of the pan and you will get more out..

But if the oil is hot will any particles that would settle in the bottom be suspended and flow out with the oil?

Duke, wha do you think is best or does it matter at all?

Joe

[Terry D.]

Re: Oil Changes - Hot or Cold?

Joe
All I know is almost every engine maker, be it lawnmower or big truck tells you in the manual to get the engine hot before draining the oil.
Terry

[Stewart A.]

Re: Oil Changes - Hot or Cold?

Joe just drain it cold. If your worried about the exhust mufflers filling with water. Its not a big deal just make sure your washer seals and dont over tighten the nut then drive the car like its stolen. Yeah !!!! (got to love reving those little 283's)

[Tom S.]

Re: Oil Changes - Hot or Cold?

Get it good and hot before draining. This way all the contaminents in the oil are drained out when you pull the plug. Otherwise part of the sludge or contaminents will lay on the bottom of the pan..

[Donald B.]

Re: Oil Changes - Hot or Cold?

"... part of the sludge or contaminents will lay on the bottom of the pan..."

Interesting point - do I want the sludge and contaminents on the bottom of the pan or do I want them circulating through the engine? I'm curious if running the engine will really "lift" the sludge off the bottom?

FYI - I've always drained the oil when hot.

[Harry S.]

Re: Oil Changes - Hot or Cold?

What will drain better from the bottle, cold maple syrup or hot maple syrup on you pancakes?

Hot!

[Michael H.]

Re: Oil Changes - Hot or Cold?

What will drain better from the bottle, cold maple syrup or hot maple syrup on you pancakes?

Hot!

I agree with Harry. HOT oil will always drain more completely and carry with it more of the trash that you don't want in your engine.
The best method is to drain when the engine is at full operating temperature, after a 20 minute drive. (not just run for 10 minutes in the garage)
Remove the drain plug and allow it to drain over night if possible and refill in the AM.

[Chuck S.]

Re: Oil Changes - Hot or Cold?

"... part of the sludge or contaminents will lay on the bottom of the pan..."

Interesting point - do I want the sludge and contaminents on the bottom of the pan or do I want them circulating through the engine? I'm curious if running the engine will really "lift" the sludge off the bottom?

FYI - I've always drained the oil when hot.

This is one of those questions I have always wondered about, but was always afraid to ask...

Actually, I think Tom is on the right track...his thinking is essentially what I've always thought, and I've always changed my oil hot; well...except maybe once after some extended thinking about this question, and temporarily deciding it didn't really make any difference. I changed back to the "hot change" position after that single change, and more extended thinking.

Assuming regular maintenance, the "contaminants" typically in engine oil are generally in liquid form dissolved in the oil...getting the engine up to operating temperature will flash off the water that leads to acid formation. Running the remaining usual contaminants "through" the engine is not a problem...leaving those contaminants in the engine for an extended time or change interval IS the problem.

One slight difference I would offer to Tom's thoughts are...if you change your oil regularly as you should, modern engines operated on modern oils do not MAKE any sludge. Today, sludge would only occur if you followed some neolithic maintenance theory like: "I never change my oil; I just add oil as needed to bring it back to full".

My definition of "sludge" (and I have seen SOME sludge) is a dark brown to black, thick, semi-solid mass of petroleum bottoms and dirt that effectively adheres permanently to all stationary engine parts, and in advanced cases, moving engine parts as well. The solids have to be removed with a scraper, and the residual left on the surface removed by aggressive solvent washing and wire brushing.

Back in the day, when an engine was neglected, sludge was not limited to the oil pan...it would be on the underside of the valve covers, the valve train, the tops of the heads, the entire oil pan, the timing chain gears/chain/cover, and inside the crankcase. So, to answer your question...No, sludge will not be sucked up out of the pan by the oil pump; it doesn't matter if the oil/sludge is hot or cold...but, it is somewhat irrelevant because once you get sludge, an engine rebuild is in your near future.

But, PRE-SLUDGE, my current, and I believe ultimately correct, thinking is that the substances that will eventually agglomerate to make sludge during overextended oil change intervals will be washed off the engine components and suspended in the hot oil for a short time after operation...on regular oil change intervals, THAT IS THE TIME TO DRAIN IT OUT before it solidifies, settles to the bottom of the pan, and attaches to all stationary parts.

As for getting your Corvette up to temperature...don't consider driving your Corvette such a burden! Like Duke says, change the oil before you store in the winter. Take a long ride, let the wind blow your hair, and do the change when you get back. Watch out for hot oil, exhaust pipes/manifolds and other engine parts.

[Joe P.]

Re: Oil Changes - Hot or Cold?

Ok.. I did my first oil change today and it was a cold one.. after all the posts I read about how messy the cannister change could be.. I decided to make it a cold one. Since I had only less than a couple hundred miles since the last oil change last spring, I thought it would be a good idea especially after reading Chucks post.

It went well until I dropped the canister .. luckily it fell into the pan that was under the oil pan.. only spilled a little oil.. good thing I put some extra cardboard down..

Let it drip for a few hours.. I put about 3/4 of quart into the cannister before I installed it.. After reading all the postts about how messy the cannister change could be. i was learay of doing a hot oil change fearing hot oil everywehre.. but it wasnt that bad.. the worst part was doing on the ground.. I filled up with a quart of EOS and CJ-4, just like Duke suggested.. But I will do a hot change at the end of this season, before the next winter storage..

Started up the engine after a long rest.. fired up on the fourth crank..

No leaks.. YAHOOO!!!..

Had a nice drive on a beautiful day.

Thanks for your input..

Joe

[Jim T.]

Re: Oil Changes - Hot or Cold?

I practice what you mention M. Hanson about draining hot oil as long as overnight. I use my old method of raising my cars from the front to get as much oil out of the oil pan as possible. I punch a hole in the spin on filter and let it drain as well. When I remove the filter it is not hot with the long drain time.

[Joel F.]

Re: Oil Changes - Hot or Cold?

Joe,

You can always drain the oil pan hot and let the engine and oil cool for several hours or even over night before removing the canister, buttoning everything back up, and refilling.

[Anthony B.]

Re: Oil Changes - Hot or Cold?

[Peter M.]

Re: Oil Changes - Hot or Cold?

Get it good and hot before draining. This way all the contaminents in the oil are drained out when you pull the plug. Otherwise part of the sludge or contaminents will lay on the bottom of the pan..

[Tom S.]

Re: Oil Changes - Hot or Cold?

This thread has some good info. I never thought about letting it set overnight, but I will do this in the future. I always put mine on ramps so that it drains to the back of the pan.I can let it set, that way as I have no where to go anyway. But I will continue to get it good and hot before draining.

[Tony H.]

Re: Oil Changes - Hot or Cold?

This might help one of us someday. If you're going to practice the overnight draining deal, it might be a good idea to place the new oil in its sealed containers on the drivers floor (make suer they are clean and not leaking) or a nice big note on the steering wheel to remind you or your significant other or son daughter or parent, that there is no oil in the motor. It would be terrible to race off the next morning only to have to have your pride and joy towed to an engine rebuild shop because the motor was run without oil.

Of course, this would probably never ever happen to any of us.