I think everyone has missed an important point here. The paranoia about cold/hot oil changes seems to assume that you are stretching oil change intervals to the maximum time/mileage “allowed” under the factory recommendations. As I’ve stated elsewhere on other threads, this is a time that only guarantees the factory that the engine will survive through the warranty period. It is too long, IMHO, for those of us who buy our vehicles new and plan to keep them well over 100,000 miles before replacing them.
Having said that, if you cut the factory interval in half or even 3/4 of the time, concerns about residual debris in the oil is a moot point. Modern filters will trap all but the finest particles that might be left in the bitter end of a long drain, so they are discarded in the old filter (you DO use a new filter with every change, don’t you?)
Drain times are essentially the same cold or hot with modern multi-weight oils. Many new cars require 5W-30 weight oils which are very thin at cold temperatures and will drain just fine at ambient temperatures. So if the oil left in your engine (maybe a couple of ounces) after a 10-minute drain is so bad that you extend drain times to half an hour and drain it hot, then you aren’t changing oil often enough. I drain better oil out of my engine than many people put into theirs because I change it more often than the book calls for. Prime your new filter if you can (some cars require it - RTFM) and don’t worry about an ounce of “dirty” oil diluted in a new gallon.
I think everyone has missed an important point here. The paranoia about cold/hot oil changes seems to assume that you are stretching oil change intervals to the maximum time/mileage “allowed” under the factory recommendations.
Some of use are sufficiently paranoid to change it much more frequently than the “book” says, use the best synthetic oil available, and let it drain for quite a while under hot (not warm) conditions. My original engine has close to 400K miles.
I have a 1989 topaz with 250,000 and change the oil and filter between 3,000 and 4,000 miles. I do it warm ( too hot burns your hand ) but have a sloped driveway so I take advantage to get e more complete drainage.
another factor in draining is the effect of temperature on removing the drain plug. too cold makes it more difficult to remove.
Id have to say that it wouldnt really matter if it was hot or cold. I would think it would be better warm because it doesnt seem to run like molasses when it is warm, but it seems to me that if the car sits for a longer period of time, most of the oil should be drained into the drain pan from the engines components. Either way you will never get 100% of the oil out, unless of course you take the engine all apart and wipe it all out, but even that is a little out of hand. One thing that you can do to help though is to park your vehicle on some sort of a slant, whether its your driveway if its slanted, or park one wheel on something that is higher than the other so that all of the oil drains out of the pan better. Ive always done that and gotten 95% of the oil that should be in the vehicle.
not to keep such a thread going ad infinitum but…
i pour in a quart of oil AFTER the original oil is done draining to flush out any remaining residue. in know, i know, it’s probably useless, but it makes me feel better seeing (after a while) clear oil coming out of the drain hole. when i see clean oil coming out, then i put the plug in.
just my opinion, as far as being AR, i guess thats what we do as auto owners trying to do ANYTHING to prolong our cars life.
When the oil warms up it tends to loosen and soften any “sludge” crud that may be in the oil system. And running the engine circulates the oil so that it picks up sediment and other settled “crud”.
I agree with Keith. It really doesn’t matter at all. You just wait until the oil stops draining until you put the plug back in. I like to do it warm but if its 90 degrees out or more convenient, I do it cold.
The service manual for my 2006 Honda Accord says to “warm up the engine”.
On the other hand, I notice that a normal oil change takes 4.4 quarts, but the capacity after an engine rebuild is 5.6 quarts. That would indicate to me that no matter what you do, hot or cold, you’re leaving 1.2 quarts of dirty oil in the engine after a normal oil change.
I change it cold. I lie down on my corregated cardboard, remove the plug, take a rest while it finishes, replace the plug and continue. Unlike Skippy Lube, I’m not in a hurry.
I’ll join others who have made the point that if you’re changing your oil and fluids regularly it really doesn’t matter if it’s hot or cold. The thing(s) that will cause you to ultimately trade the car in will be unaffected. In reality, properly maintained engines very rarely wear out. When they do it’s generally things that are going to happen anyway, like the rings lose their spring tension or the engine overheats and damages the mains, or external pieces fail or corrode away. Or a headgasket blows.
I’ve never worn an engine out in 40 years of driving, except that '72 Vega, and that was Chevy’s fault…they admitted it.
What you say is true about multi viscosity oils when being drained. What do you think about the latest manufacturer recommendations about using 5W-20 oil? For sustained, high speed, high temperature driving, I have long thought that something like 20W-50 or 15W-40 is better at protecting the engine. But it won’t work in Minnesota in the winter, of course!
What do you think about the latest manufacturer recommendations about using 5W-20 oil? For sustained, high speed, high temperature driving, I have long thought that something like 20W-50 or 15W-40 is better at protecting the engine. But it won’t work in Minnesota in the winter, of course!
I would still follow the manufactures recommendations, unless there was a compelling reason to do something different. Sometimes they give a range of recommended oils based on temperature, and you can pick a higher viscosity oil from that range. Also, the mobil 1 web site gives specific (mobil) recommendations based on the make/model of car, they may give you some alternatives:
I have done thousands of oil changes on fleet vehicles, that all get sold after they hit 200,000 to 250,000 miles (with the original engine). The only time I believe it makes a difference is when it is winter here in Wisconsin (then I run it a little while). Today in July @ 85 degrees out, just drain it “cold” so you aren’t uncomfortable. BUT, if you can (like on my Chevy trucks), always prefill the oil filter !!! Otherwise the startup after draining all the oil (and the oil pipe hoses to & from the auxiliary oil cooler) probably does as much damage as a person is trying to prevent…