Check oil when engine is hot or cold?

"HLS" snipped-for-privacy@nospam.nix wrote in news:dxhnk.14879$ snipped-for-privacy@nlpi065.nbdc.sbc.com:

And, I have found, that only happens completely if the engine sits undisturbed overnight.

I've spent the last seven months (covering some 8,400 miles) doing extremely precise measurements of my oil consumption. Each and every check (seven recorded checks so far, many more unrecorded) has been done in exactly the same manner. Precision is critical for anything like this.

Now, I am confounded by one imprecise factor, and that is the actual stick reading, which is done visually against a millimeter-graduated scale I devised for the purpose. I have found that, not only does oil take all night to fully drip down into the pan, but the stick reading is different from front to rear on the stick. In addition, each time you pull the stick to check and put it back, the next reading may vary by as much as 1/2 a millimeter from the previous one unless you wait five minutes or so between stick pulls. In addition to all that, the level indicated on the stick may not be a flat line, but may be concave or convex, this apparently random, but surely tied to something I haven't discovered yet. All this means it is difficult to pin oil level to an exact reading, or consumption down to anything finer than 50 or 100 mile increments.

These are my readings. Odometer is in kilometers, all else is US Imperial: Jan 23/08 - 477,832 to 479,441 - 2,500 mi/qt - avg temp about 10 - 1st thousand on oil Feb 20/08 - 479,624 to 481,233 - 2,175 mi/qt - avg temp about 10 - 2nd thousand on oil Mar 28/08 - 481,975 to 483,551 - 2,500 mi/qt - avg temp about 30 - 1st thousand on oil Apr 17/08 - 483,583 to 485,268 - 2,350 mi/qt - avg temp about 40 - 2nd thousand on oil May 11/08 - 485,721 to 487,373 - 1,650 mi/qt - avg temp about 50 - 3rd thousand on oil Jun 14/08 - 487,963 to 489,663 - 2,150 mi/qt - avg temp about 65 - 1st thousand on oil Jul 03/08 - 489,699 to 491,418 - 1,800 mi/qt - avg temp about 75 - 2nd thousand on oil

This gives me an average consumption of about 2,100 miles per quart. Oil age seems to be a factor in consumption, as does ambient temperature. In a year or so I should have enough data to determine more convincingly the most important factors governing my oil consumption.

Reply to
Tegger
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You are trying to be too precise. Many things can affect oil consumption, especially on a worn engine. Acceleration, traffic conditions, driving practices in general, temps, etc, etc. Here's something to ponder. I rebuilt a 352, jobbing only the case bath, cam bearing insertion and the heads. Ran perfect, but was using a quart of oil every 500 miles or so with the mostly city driving I was doing. I suspected the valve guides, since I had jobbed the heads. This was confirmed when I took a trip to Yellowstone, driving about

4000 miles total, and used no more than 1/2 quart of oil for the trip. Back home in the city, pulling vacuum when backing off for lights and stop signs started sucking the oil through the guides at the same quart per 500 miles.

--Vic

Reply to
Vic Smith

My father was a master mechanic and instructor at a major Army base near Washington DC in the 1950s, and, as you know, the Army has a process and procedure for everything. For oil, this was they way you did it.

-john-

Reply to
John A. Weeks III

OK. It makes more sense in that context. I was in the Army in the 70's. Saw lots of weird stuff in those manuals.

Reply to
E Meyer

It is not a completely dumb procedure. With the engine running you don't want too much oil because the crank will whip it like an egg beater and you don't want too little or the pump will suck air. So a test that takes into account how fast it can get back to the pan does make some sense.

-jim

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Reply to
jim

Warm engine, level ground, a few minutes after turning it off (e.g. after fueling).

If you want to know your burn rate, you want a /consistent/ and /convenient/ method. If you are driving across the country, you can't wait for the engine to cool each time you check the oil, so you do it when the engine is warm.

Get it?

Reply to
Matt

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