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| Why would my truck lose oil only on long trips? (Page 1/1) |
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CowsPatoot
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DEC 18, 03:15 PM
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2001 Silverado Z71, 5.3, auto, 215k miles. Engine has run Mobile 1 synthetic it's entire life. Engine runs like new.
In the past couple years, I don't put a lot of miles on the truck (comparatively...I guess I still average close to 15k per year). Normal driving is around town on short trips...but I tend to take several long trips (700 miles +) per year in the truck. I admit that I am not in the habit of checking the oil in the truck because it never seems to be low when I do check it...but for about 2 years it seems that on every long trip I take, my "Check Engine Oil Level" light comes on. This comes on when it is about a quart low. For two years now, I have assumed that it has been slowly consuming some oil, and since a large portion of it's miles are on long trips, there are good odds that it will hit that point on a long trip. But it now seems that isn't the case.
My truck is do for an oil change. Last oil change was done by me about 7300 miles ago. I have not put oil in it since then. I checked the oil yesterday morning before my long trip...the oil level was fine. About the time I showed up at my mother's house 3 states away, the "Check Oil" light came on.
So....why would long trips cause it to lose oil?
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weaselbeak
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DEC 18, 04:37 PM
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The engine is maintaining a much higher average rpm, so there is a higher possibilty of oil consumption as the vacuum during the intake stroke will be increased, pulling some oil up past the rings from below. My tech explanation for that may be wrongfully stated, but I understand it anyway.  You will also be running your max oil pressure at those higher speeds, so any tiny leaks might get magnified. There should be, I think, more oil hanging around those 215K valve seals to leak past a bit. Probably just a combo of small things that add up during higher engine speeds. I had a brother-in-law who went thru some genuine GM tech school training in a Cadillac factory back in the 70's, and they told him an engine that used a wee bit of oil (called it a "wet" engine), would have a longer engine life. I doubt that applies in today's applications, but I thought it was an interesting statement at the time. Given the oil burned by my Grand Marquis with 170k gentle miles on it, I'll trade you problems.[This message has been edited by weaselbeak (edited 12-18-2012).]
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CowsPatoot
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DEC 19, 11:01 AM
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So....My truck accepts the fact that I am going to smoke a cigar in it on these long trips, and it doesn't complain. In return, I should accept the fact that it will drink a little oil, and should quit complaining about it. I can accept that.
Thanx for your thoughts.
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Stubby79
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DEC 22, 10:13 AM
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And was it reading low on the dipstick when you got to your mother's house? A key bit of information I don't want to assume. Checked your PCV valve and related components?
If you weren't running synthetic, I'd blame the oil for breaking down.
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CowsPatoot
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DEC 22, 07:44 PM
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| quote | Originally posted by Stubby79:
And was it reading low on the dipstick when you got to your mother's house? |
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Yes...it really was low. I shouldn't have left that to be assumed.
| quote | Originally posted by Stubby79:
Checked your PCV valve and related components? |
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No...I haven't. And the PCV valve is original. Perhaps it is time for some standard maintenance on this truck. After thinking about it....the only thing that HAS been replaced under the hood of this truck is the air filter, oil and filter every 7500 miles or so, a new starter at 170k miles, and a new battery at 190k. Even the spark plugs are original. Thanx for your thoughts. After hearing it, I feel foolish for NOT checking that.
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Stubby79
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DEC 24, 10:00 AM
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Well then...you can have a look at those spark plugs when you change 'em and see if you've been burning the oil or not and if it's all cylinders or just a few. If you're lucky, it's just that valve!
Edit: Maybe the bullitins on oil consumption will give you an idea. Looks like there might be an updated PCV valve for your engine (3rd bulliten listed on this page)
http://www.performancetruck...-consumption-351904/[This message has been edited by Stubby79 (edited 12-24-2012).]
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