Soooo . . . . an easy one, but interesting. Oil change tomorrow morning. Shall I drain the oil after it(the car) has sat all night without starting it up/warming the engine or start it up, run 'till warm then change? Is it better to have all the junk drain down into the pan overnight or better to get it warm and drain it immediately when warm?
Y’know, it doesn’t really matter.
I do all my own oil changes. I used to insist on changing only warm oil. All that does is allow the used oil to flow out a little faster and maybe you will get out a few more drops.
So what? By the time I have removed and replaced the oil filter I’ve drained maybe 98% of the old oil no matter whether it started out pre-warmed or at ambient temperature. Close the plug and re-fill. A few extra drops of the previous oil does no harm at all.
I always do it when the engine is warm. I wonder if it really matters, however.
I always do it hot, I get more oil out faster. I also burn myself every time I change the filter. Sometimes I remove the drain with it hot and let it sit for about an hour draining, that gets more oil out, and I burn myself less. I know some folks who drain it cold and let it drain overnight, it probably doesn’t make very much difference.
The old oil will come out a lot quicker if it is warm. You don’t have to drive or run it for more than a short trip of maybe five miles or so, if you want the oil to be warm.
I’ve always been told to change the oil when it’s warm, since it stirs up any debris or gunk and will get that out with the old oil. Whether that’s true or not, I don’t know, but I always change the oil when it’s warm or hot. I also wear an old pair of black gloves when I do it, so I don’t get oil all over me, and so I don’t get burned from the drain plug or the oil filter.
I dunno how well it works, since the one I got doesn’t seem to fit on my chevelle.
Change it warm. Open the plug to drain it and let it sit like that for 30 minutes to get the maximum drainage. You will never completely drain the motor regardless of how you do it but this method is very effective. I do my own oil changes and all my engines reach 200,000 to 300,000 with no problems.
I think this kind of question is for people who are a bit anal retentive. The most important thing about an oil change is that it gets done, hot or cold is not nearly as important as the schedule.
I agree, just do it.
With my RAV4 the side mounted oil filter tends to be empty when the engine is cold and therefore it is less messy cold.
Well, I changed it COLD and drained almost 4 full quarts (the fill is four full quarts). It is somewhat easier to change cold for me because this particular car has an oil filter which will spill oil on the engine, exhaust and ground if full. It seems that even with the anti-drainback valve on this oil filter, that it is less full of oil than when warm or just recently run. Anyway, thanks for the responses . . . I guess that however you do it Keith is right (except the anal part), just do it on a regular basis.
Sorry, I apologize for the anal remark
I had an 83 Camry that used to drain the oil filter if I waited five minutes after shutting it off. I was happy to get no oil all over the place. If they made that car again I would like to buy one. The timing belt could be changed without disconnecting the upper engine mount and the plugs were looking right at you. It seemed as if there was a lot of space under the hood. The 82 Honda I had was a real headache for working under the hood.
Warm oil speeds up the process. Hot oil slow it down after you get burned.
It really does not matter.
interestingly, with the multiweight oils which are pretty much the standard, the oil is actually thinner(viscosity) cold than it is warm. So technically it should come out faster cold than warm.
I have a theory that long extended drain time with the oil filter and drain plugs removed to get every last drop of old oil out is actually bad. My reasoning is this drains all the oil out of the oil pump, crucial oil passages and bearings. So now the first start after the oil change will take longer for the pump to prime itself while the bearing are dry. I simply put in a little new oil and let it drain to flush the crud out. Opinions welcome.
The biggest factor in the time to regain oil pressure after a change appears to be the time required to refill the filter. In my car it takes about 3-4 seconds for the oil pressure to come up after a change (I have a large oil filter canister, not a spin-on filter. I doubt the oil pump will “lose it’s prime” on many cars.
Actually that’s not true, The cold oil is still more viscous than the hot oil, just less viscous than it would be with single weight oil. For example 5W40 oil looks like cold 5W and hot 40W, cold 5W is still much more viscous than hot 40W. Cold 40W would be even more viscous. Try draining it hot and cold and see for yourself.