Warm engine prior to oil change ?
I'm getting lazy; my 65 BB has been sitting in the garage for 2 months without running. Can I change the oil and filter cold, and expect that the contaminants will drain as thoroughly as if it were hot ? I would let it drain overnight.
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Re: Warm engine prior to oil change ?
You may get a million different opinions, but I would think a hot engine AND the all night drain would be ideal !
Tom Hendricks
Proud Member NCRS #23758
NCM Founding Member # 1143
Corvette Department Manager and
Specialist for 27 years at BUDS Chevrolet. -
Re: Warm engine prior to oil change ?
Go for it Wayne. You wouldn't be the first to commit such a sin- and survive.
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Re: Warm engine prior to oil change ?
On the other hand.... if the engine was at operating temp when it was shut down two months ago, all of the hot oil and all of the goonk has had two months to make it's way to the oil pan instead of hanging around up above.
I dunno.Comment
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Re: Warm engine prior to oil change ?
Oil should always be drained hot - at least a half hour of normal driving in mild temperatures.
It's a good idea to check that you can move the filter (or filter housing bolt if it still has the OE cartridge filter). It can happen that you drain the pan and then find the filter won't come off. Now what do you do?
While the oil is draining, R&I the filter and fill it to near the top with fresh oil before installing.
I'm assuming you have a rear facing drain plug and if you elevate the front of the car as much as possible, all the oil should drain out. It shouldn't take more than 15 minutes and maybe as little as five.
I DO NOT RECOMMEND letting it drain overnight. That's an intenet myth. It's better to start the engine hot - it should start faster - and the oil will be warmed up by picking up engine heat as it drains from the fill point to the pan.
Once you check that the filter is properly installed and the pan plug is in, fill with appropriate oil. I assume you know the best API service category and viscosity, so I won't beat on that issue again.
Start the engine and watch the oil pressure gage. It should come up within five seconds. Once you have pressure check under the car for leaks.
DukeComment
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Re: Warm engine prior to oil change ?
Duke, if you pre-fill the oil canister, isn't it going to leak out around the bolt hole? -Dan-Comment
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Re: Warm engine prior to oil change ?
Right - a drop or two, if that. Fill the cannister about half full with oil. Then slowly drop in the filter element. If you want, slowly add more oil down around the center bolt until the level in the cannister is about and inch or two from the top. Install the cannister, spritz the bottom with some paint thinner and wipe off to remove any oil seepage.
If you don't know how old the gasket is, you should replace it. Remove the bypass valve assembly and thoroughly remove the old gasket. Apply some grease, sparingly, to the gasket seat and install the gasket. Make sure it is properly seated then install the bypass assembly followed by the cannister. I recommend changing the gasket ever other filter change.
Once, a looooooooong time ago, I didn't get the gasket properly seated and dumped three quarts of oil on the ground before I realized I had a leak.
DukeComment
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Re: Warm engine prior to oil change ?
Wayne,
Being an ole 396 make a couple of hard passes at 6500 rpm between each shift and it will blow all the old oil out and all you gotta do is add 4-5 qts
LOL
CarlComment
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Re: Warm engine prior to oil change ?
On vintage Corvettes, yes. My cars that have spin-on filters have them mounted either horizontally or "upside down", so I don't have that option, and it takes a few extra seconds for oil pressure to come up.
If you can mostly fill the filter, oil pressure should come up within a second or two rather than 3-5 seconds if you can't fill the filter.
BTW, if you have cars that have upside down filters, they will drain while the oil is draining from the pan if you punch a hole in them with a center punch or big nail, however, in this case be sure you use the filter wrench to make ABSOLUTELY sure the filter will move before you punch the hole. If the filter is seized and you hole it, you are up the creek without a paddle.
Once the pan is drained you can reinstall the plug and fill the pan. Last step is to remove the filter and there should be very little oil spillage. Install the filter and it's ready to start, pressure check, and leak check.
DukeComment
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Re: Warm engine prior to oil change ?
Duke, is there any other reason other than warm restarting, that you DO NOT RECOMMEND overnight draining? I do like to get more of the old oil and possibly sludge out by overnight draining, have not had a problem yet.
Steve
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Re: Warm engine prior to oil change ?
I fill the vertically mounted spin-on filters on ALL my cars to the top -- dip a finger in the fresh oil and then lube the new gasket. Most of the spin-on filters have instructions to tighten 3/4 turn after gasket contacts the mount, but if you are really anal there are torque values in the AIM.
TerryComment
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Re: Warm engine prior to oil change ?
The engine will start faster and oil pressure will come up more quicky if the engine and engine oil is hot, and the residual heat in the engine will warm the newly installed oil.
A cold engine and empty oil filter is the worst case. Usually longer cranking time and an empty filter and oil pressure will take several seconds longer to come up than a hot engine and full filter.
Oils have dispersants than help keep contaminents in suspension, but they can settle out to the bottom of the sump until churned up by the next operational cycle.. Think of a bottle of salad dressing - shake well before using, and if it's stone cold, it won't flow out of the bottle very well.
Draining the oil hot as soon as possible after engine shutdown from at least a half hour of normal operation is the best way to get contaminants out. (This applies to transmissions and axles, too.) If you use a proper oil and change it at a reasonable frequency the engine will not sludge up. Tilt the car to get the drain plug as low as possible and reinstall the plug after the dripping stops. Leaving the plug open for several more hours won't net more than an ounce or two, which is meaningless, compared to the downside discussed above.
Some manufactures specify both a "dry fill" and "refill" specification. The dry fill would be for a newly assembled engine, and the difference is usually in the range of half to one quart. So even if you let the oil drain overnight - or six months for that matter - there will still be a lot of oil inside the engine that clings to surfaces and gets trapped in nooks and crannies.
My SWC engine had no sludge when I rebuilt it in the seventies, and the oils back then were nowhere near as good as today. Proper oil, change intervals, and a properly functioning PCV system will prevent sludging. Sludging in modern engines is almost unheard of, but there have been some modern engines that seem more suspectible to it - probably due to inadequate crankcase ventiliation. Then there are the morons who almost never change their oil, but none of us should be in that camp.
Lastly, who recommends letting the oil drain overnight. Do any OEMs recommend it? No, the "internet" invented it, and nobody knows of a reputable source for the myth, other than my buddy said... or I read it on an internet forum from bigblockbubba.
DukeComment
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