Oil Changes - Hot or Cold?

[Tom S.]

Re: Oil Changes - Hot or Cold?

Placing the oil jugs near the car is a good idea. Also removing and hiding the keys is a good idea. But be sure to write yourself a note to remind you where you put the keys! And another note as to where the first note is! This part of this thread is just for all us old guys of course!

[Duke W.]

Re: Oil Changes - Hot or Cold?

I don't think letting the oil drain overnight is a good idea for the reason that you are now doing a cold start rather than a hot start.

On any car, if you jack up the appropriate corner or end of the car to facilitate draining, once the flow of hot oil is down to a slow drip you are done and have drained about 95 percent of the oil out of the engine. Letting it sit overnight maybe gets another one or two percent - BFD. If you follow recommended oil change intervals the old oil should not appear to be very dirty or contamiated.

Prefilling the oil filter is a good idea if the design facilitates this as it does on vintage Corvettes.

The hot engine will heat up the fresh oil so it will easily flow and purge any remaining air pockets to achieve oil pressure within a couple of seconds of engine start.

Duke

[Michael H.]

Re: Oil Changes - Hot or Cold?

I don't think letting the oil drain overnight is a good idea for the reason that you are now doing a cold start rather than a hot start.

Well.... yeah, but if you refill the hot engine with cold oil, then wait to start it the next morning to go for a ride around the block, yer back to cold engine and cold oil. Same thing.

I suppose that restarting the hot engine immediately after changing oil might be better IF the oil filter weren't prefilled before installation.

[Duke W.]

Re: Oil Changes - Hot or Cold?

I assume people understand that the final step of an oil change job is starting the engine, checking that the oil pressure comes up to normal levels, and then checking for leaks.

The job isn't done until the QA is completed! Isn't that obvious?

Duke

[Michael H.]

Re: Oil Changes - Hot or Cold?

I assume people understand that the final step of an oil change job is starting the engine, checking that the oil pressure comes up to normal levels, and then checking for leaks.

The job isn't done until the QA is completed! Isn't that obvious?

Duke

Yes, but much easier on a cold engine.

[Chuck R.]

Re: Oil Changes - Hot or Cold?

Dump the oil as close to engine shut down as possible.

This way whatever form of suspended solids that may be mixed in with the oil at that time doesn't have a chance to separate and settle.

As Duke stated, re-starting a warm engine is far less stressful on close tolerance components as they still retain a good film of lubricant.

Finally, if I have a lubrication issue brewing from an oil change, I would much rather find it out right after the oil change with everything at operating temperature, when the oil is at it's thinest consistency rather than jump in my ride with my white Dockers on and find out that I'm trailing or burning off raw oil.

Quick story (Really)
My now Brother In-law was in a hurry to pick up his date after changing the oil in his ride. He plowed in the oil, took a shower and to his amazment upon returning to the car, found a small ocean of wonderful honey gold oil running down the driveway.
Five quarts went straight through the mill to the cardboard (where laid the drain plug and wrench), then to the garage floor and eventually out to the driveway.

The moral to that story is not to hurry the job, and double double check everything you had your hands on. I don't care if a person has done one or one thousand oils changes. Brain cramps can happen. It's a terminal thing with me these days

Chuck

[Michael H.]

Re: Oil Changes - Hot or Cold?

Dump the oil as close to engine shut down as possible.

This way whatever form of suspended solids that may be mixed in with the oil at that time doesn't have a chance to separate and settle.

As Duke stated, re-starting a warm engine is far less stressful on close tolerance components as they still retain a good film of lubricant.

Chuck,

I agree with most of that but starting the engine hot after the oil change isn't going to be any different than starting the engine the next day when it's cold. Any time an engine is shut down hot, most of the oil runs off the moving parts and back into the oil pan. Having fresh oil in the oil pan won't have any effect on the amount of oil that's still on those moving parts.

If you drive your car, eventually you're going to have to shut it off and, when you do, most of the oil is going to return to the pan, just like when you change the oil. It's exactly the same with old oil or new oil. When you start a cold engine, it takes a few seconds to get oil back to all the moving parts.

[Stewart A.]

Re: Oil Changes - Hot or Cold?

I biult a nice little Ford 289 15 years ago. New nothing about motors but bumbbled along and got it in to the car. I ran it every day for fifteen years then decided it wasn't fast enough for my wife. (yeah sure).
I pulled the motor out and was completely baffled I thought I would see yuk evrywhere. Now back then I new nothing about motors. There was not one ounce of build up anywhere on motor nothing worn no sludge no nothing except shinny clean metal parts it looked brand new. Now I put that down to this, I changed my oil every time it looked like going black. I always had a honey dip stick. I changed it every 3000 miles. Now that seems like alot of changing oil but the proof was in the pudding. I could still see the cross hatch in the bores and the bearings showed very little wear no glazing and no wear. I changed it cold sometimes but mostly hot as to get most of the yuk out. I used a Castrol gtx nothing to sophisticated, just a regular change. Isn't it amazing how a basic thread of an oil change can become so scientific. Drive and enjoy your Corvette you have something special.

[Troy M.]

Re: Oil Changes - Hot or Cold?

FYI: You will never get all of the old oil out. At least I hope you don't. The bearings would seize the moment you cranked the starter.

Hot or cold, it doesn't matter.......................

[Chuck R.]

Re: Isn't America great Mike

I don't have to worry about you coming over to my house and killing my family because we philosophically disagree

I think this is one of those potato potato discussions that end up dead locked

[Michael H.]

Re: Isn't America great Mike

I don't have to worry about you coming over to my house and killing my family because we philosophically disagree

I think this is one of those potato potato discussions that end up dead locked

Yup, this has been a fun discussion. Amazing how much time we spend discussion minute details about things that really don't make much difference anyway.

As long as we get MOST of the old oil out at least once every 10 years, we should be ok.

(by the way, the last time I changed the oil in the 66, it was cold and I only allowed it to drain for about 5 minutes)

[Chuck R.]

Re: Heck Mike I got ya beat

As you are well aware, I drop mine hot in about 2.5 minutes INCLUDING THE FILTER

As my ride is still a bare chassis, my next oil change will probably be in the range of August 2009

Chuckster

[Terry M.]

Re: Oil Changes - Hot or Cold?

This is beginning to sound like BobIsTheOilGuy. You want to obsess about oil that is the place to join fellow oil-based obsessive compulsives. Check it out

https://www.bobistheoilguy.com

Actually there is a lot of good information over there about lubrication in general, as well as oil for old and new cars.

[Chuck R.]

Re: Just some good natured fun Terry

I'm good.

I'll take my 30 weight and check out the web site now

Chuck

[Terry M.]