Home » Public Forums » GMCnet » [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed.
Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. [message #336528 is a reply to message #336507] |
Wed, 29 August 2018 23:50 |
johnd01
Messages: 354 Registered: July 2017 Location: Sacrameot
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What does changing the oil weight do the oil pressure? I feel my oil
pressure is low. Would like to have a real gauge. Coach has 117k miles. OP
said it was reabuilt at 100k.
On Wed, Aug 29, 2018 at 12:26 PM James Hupy wrote:
> My engine has had frequent oil changes and proper maintenance throughout
> its service life. It suffers the same problems as many of the motorhomes.
> Long periods of inactivity. That is a definite no - no. Better to take
> short warmup drives of 20 miles or so every couple of weeks. Keeps
> everything lubed, and brakes and all systems operating.
> Jim Hupy
>
> On Wed, Aug 29, 2018, 12:13 PM Les Burt wrote:
>
>> Thicker oil generally means a thicker oil film on the cylinder walls. It
>> is my belief that the thicker oil film can overload worn or stuck oil
>> rings, increasing consumption.
>>
>> I’ve actually seen a few engines where a thinner oil helped reduce oil
>> consumption. Didn’t get to pull them apart for a proper diagnosis, so I
>> can’t say if it was the guides/seals, or rings that were worn.
>>
>> Thicker oil can also overwhelm the pcv system on engines with excessive
>> blowby. Seen this happen a few times on some worn out engines.
>>
>> Les Burt
>> Montreal
>> '75 Eleganza 26'
>>
>>
>>> On Aug 29, 2018, at 2:22 PM, James Hupy wrote:
>>>
>>> My 403 when I first got it, had 87,000+ miles on the clock. P.O. had
> been
>>> using 10w - 30 dino oil in the engine. Consumption was 800 or so miles
>> per
>>> quart, which I thought was a bit high. My mechanical fuel pump gasket
> was
>>> leaking a bit of oil, so I fixed that and cleaned up all the surplus
>> stuff
>>> on the outside of the block. Ran long enough to tell that oil
> consumption
>>> didn't change much. Darn. So, I decided to change to Valvoline 20w -
> 50.
>>> Oil consumption changed to a quart every 1200 to 1500 miles. That is
>> where
>>> it is today with over 125,000 miles on the engine. Compression is
>>> consistent at 150 psi across the board. So, the old girl is going to be
>>> driven like she is, until something changes dramatically. Factory says
>> that
>>> a qt per 500 miles is acceptable. I think that borders on excessive
>>> consumption, while the factory is covering their butt on warranty
> claims.
>>> Jim Hupy
>>> Salem, Or
>>> 78 GMC ROYALE 403
>>>
>>>> On Wed, Aug 29, 2018, 10:41 AM Bob Dunahugh
>> wrote:
>>>>
>>>> Sully. Don't know when most of the oil consumption would occur. Never
>> even
>>>> saw a hint of oil smoke ever. Thought that the 50 might help some. It
>> did.
>>>> Bob Dunahugh
>>>>
>>>>
>>>> ________________________________
>>>> From: Bob Dunahugh
>>>> Sent: Monday, August 27, 2018 9:53 PM
>>>> To: gmclist@list.gmcnet.org
>>>> Subject: Tid Bits: Oil consumption. It's all in how/where it's
> consumed.
>>>>
>>>>
>>>> 6 years ago. I knew someone that got very upset that their engine
>>>> consumed one qt every 300 miles. So we looked at the spark plugs. All
>> the
>>>> spark plugs showed about the same as to discoloration/deposits. The
>>>> compression test came in at reasonable numbers. At 115 to 123 psi. Not
>>>> great. But not bad. Inspection camera showed oil washing around the
>> edges
>>>> of the pistons. All washing on all pistons was about the same width.
>> Again.
>>>> Not a great sign. But not bad. Just expected. Put a dial indicating
>>>> micromotor to the top of each rocker arm. Just looking for consistency
>>>> between all the intake. Then all the exhaust. Looked good. But that
> test
>>>> doesn't show how much the lifters are dished. Or how much of the cam
>> lobes
>>>> are gone. Again used the inspection camera to check the cam
> gear/chain.
>> Had
>>>> been changed at some past point. Warm oil pressures were13psi at
> idle.
>>>> 21psi at speed. This is a candidate for a high volume oil pump. But
> the
>>>> pump could over load the piston oil control rings. That are already
>> over
>>>> loaded. Thus it could up oil consumption. I suggested running it as
> is.
>> And
>>>> run a heavier oil. He's been using 20W50 oil. Still running well. Oil
>>>> consumption has been at about 400 miles per qt. If the engine had all
>> the
>>>> oil consumption issues in just one or two cylinders. That's time for a
>>>> rebuild. As for what's best for you. Not my monkeys. Not my circus.
> Bob
>>>> Dunahugh
>>>> _______________________________________________
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--
*John Phillips*
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Johnd01
John Phillips
Avion A2600 TZE064V101164
Rancho Cordova, CA (Sacramento)
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