Evaluating a Used Car - DipStick (Oil) Reading

"april1st" > wrote in message
ups.com...
> They oil may be contaminated due to excessive blow-by caused by worn
> out piston rings among many other things --


To separate the blow-by hypothesis from the other things, could it be as
simple as removing the oil filler cap and seeing how much smoke comes out? A
compression test might be better, but the smoke test is fast and free.

Blake wrote:
>
> "april1st" > wrote in message
> ups.com...
> > They oil may be contaminated due to excessive blow-by caused by worn
> > out piston rings among many other things --
>
> To separate the blow-by hypothesis from the other things,

You can't separate the "blow-by hypothesis" because that theory is
incorrect. If you change the oil often enough you can keep the inside of
any engine clean even if it burns a quart of oil every 50 miles and it
has compression of 50 lbs. and leaves a trail of blue smoke wherever it
goes.
It may well be that because the oil wasn't changed often enough the
rings are more worn than they otherwise would be. And/or it may well be
that because the engine used a lot of oil the previous owner thought
that the oil didn't need to be changed very often because they were
always adding oil. So there may well be a correlation between the
appearance of black oil and blow-by. But the cause of the oil being
black is not blow-by. It is either they didn't really change the oil as
the salesman said or the engine has a history of the oil not being
changed as often as some people do. In my opinion its unlikely that they
skipped the oil change if they were seriously trying to sell the car. As
for the other theories that they didn't drain all the oil or didn't
change the filter - it is much more likely that the previous owner was
the one doing those things. The dealer probably changed the oil and
filter properly.

-jim


>could it be as
> simple as removing the oil filler cap and seeing how much smoke comes out? A
> compression test might be better, but the smoke test is fast and free.

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

Joe wrote:

> "HKEK" > wrote in message
> oups.com...
>
>>I'm looking at a 2002 Dodge Grand Caravan 3.3L with 57,000 miles. I
>>pulled the dipstick and the oil looked dark and smelled a bit cooked.
>>The vehicle had been taken in trade at a [Dodge] dealer. The salesman
>>showed me the shop work that had been performed on this vehicle to
>>ready it for resale. Among other things such as brakes and stabilizer
>>bushings, the engine oil and filter had been changed. The van had
>>about 50 miles on it since the oil change.
>
>
> It's hard to say. Likely as not, they falsified the work report.

My first thought also. It would be rather hard to *truly* damage a 3.3
in only 57k miles. Yeah, extreme, extreme neglect would do it, but that
should be fairly obvious in other ways. I bet they just didn't change
the oil.

In article .com>,
HKEK > wrote:

> I can have the vehicle inspected and the deposit is refundable if my
> mechanic finds any serious issues.
>
> It has been suggested that some shops do not drain the oil during
> changes but pump it out instead through the dipstick tube. It was
> further suggested that this practice may leave enough used oil behind
> to contaminated the fresh oil being added.
Correct.
>
> When I drain oil for a change, I drain it hot and for an hour or two
> if not overnight.
That's how I do it.
The shop I go to does remove the drain plug for about 15 min.

Over the years I've noticed very very dirty oil in some rental cars with
over 15K miles on the clock. I'm sure they only change the oil just
before selling the rental. How to shorten engine life!
I'll not mention the worst rental car oil I've noticed, not wanting to
be sued! <

After doing a little test, I believe the oil had been changed before I
put a deposit on this car.

I had the dealer change the oil and filter and I drove the van around
for about 15 miles. I then collected some of the oil from the dipstick
into a glass vial. I repeatedly insert the dipstick into the
crankcase, withdrew it, and wiped into the glass vial.

The dealer saved some of the original oil in a glass jar.

I also got a sample of the fresh oil, which was Citgo 5W30.

Well, the original oil was very dark and smelled a bit like gasoline.
The fresh oil was very clear, a bit yellow, and had little scent. The
oil that had been in the crankcase for 15 miles looked about half as
dark as the original oil and also smelled a bit like gasoline.

Does this mean anything of significance? I think the previous owner(s)
ran the car beyond the recommended service intervals (oil & filter
change) and I believe the fresh oil, with its detergents, is cleaning
up deposits on engine surfaces.

I will have a compression check run on the front 3 cylinders (the back
3 are require removal of the intake plenum).

If I end up buying this one, I will probably change the oil at
extremely short intervals (~100 miles or weekly) until the oil stays
clear.

On Wed, 23 May 2007 19:01:11 -0700, HKEK wrote:

<snip>

> If I end up buying this one, I will probably change the oil at extremely
> short intervals (~100 miles or weekly) until the oil stays clear.

Correction - if you end up buying it, you'll be an even bigger fool than
you appear to be now.

--
"Ubuntu" -- an African word, meaning "Slackware is too hard for me".

HKEK wrote:
> After doing a little test, I believe the oil had been changed before I
> put a deposit on this car.
>
> I had the dealer change the oil and filter and I drove the van around
> for about 15 miles. I then collected some of the oil from the dipstick
> into a glass vial. I repeatedly insert the dipstick into the
> crankcase, withdrew it, and wiped into the glass vial.
>
> The dealer saved some of the original oil in a glass jar.
>
> I also got a sample of the fresh oil, which was Citgo 5W30.
>
> Well, the original oil was very dark and smelled a bit like gasoline.
> The fresh oil was very clear, a bit yellow, and had little scent. The
> oil that had been in the crankcase for 15 miles looked about half as
> dark as the original oil and also smelled a bit like gasoline.
>
> Does this mean anything of significance? I think the previous owner(s)
> ran the car beyond the recommended service intervals (oil & filter
> change) and I believe the fresh oil, with its detergents, is cleaning
> up deposits on engine surfaces.
>
> I will have a compression check run on the front 3 cylinders (the back
> 3 are require removal of the intake plenum).
>
> If I end up buying this one, I will probably change the oil at
> extremely short intervals (~100 miles or weekly) until the oil stays
> clear.

Hi..

The real question is how fast can you run? And how quickly
can you start?

Take care.

Ken

In article om>,
HKEK > wrote:

> After doing a little test, I believe the oil had been changed before I
> put a deposit on this car.
>
> I had the dealer change the oil and filter and I drove the van around
> for about 15 miles. I then collected some of the oil from the dipstick
> into a glass vial. I repeatedly insert the dipstick into the
> crankcase, withdrew it, and wiped into the glass vial.
>
> The dealer saved some of the original oil in a glass jar.
>
> I also got a sample of the fresh oil, which was Citgo 5W30.
>
> Well, the original oil was very dark and smelled a bit like gasoline.
> The fresh oil was very clear, a bit yellow, and had little scent. The
> oil that had been in the crankcase for 15 miles looked about half as
> dark as the original oil and also smelled a bit like gasoline.
>
> Does this mean anything of significance? I think the previous owner(s)
> ran the car beyond the recommended service intervals (oil & filter
> change) and I believe the fresh oil, with its detergents, is cleaning
> up deposits on engine surfaces.
>
> I will have a compression check run on the front 3 cylinders (the back
> 3 are require removal of the intake plenum).
>
> If I end up buying this one, I will probably change the oil at
> extremely short intervals (~100 miles or weekly) until the oil stays
> clear.

Just fill the crankcase with diesel fuel instead of oil and run it at
temp for five minutes or so. Diesel is a good lubricant, so no harm to
the engine, but it's also high detergent, so it'll clean. Then drain &
fill with motor oil. Do that at your next two regularly scheduled oil
changes and your engine ought to come clean unless it has other
problems. No need to waste a bunch of motor oil and filters.
I always put a quart of diesel fuel in my engine a day before I do an
oil change to keep everything clean. On lawnmowers I'll actually fill
it up with diesel and mow a lawn.

--
B.B. --I am not a goat! thegoat4 at airmail dot net

Sounds like the oil is filling with gas. This will 'fast' destroy the
engine if it already hasn't done so.

A compression test will not tell you about all the dead crank and cam
bearings, only the rings and valves which aren't parts killed fast by
gasoline diluted oil.

You really need an oil analysis on it or to just walk away now.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

HKEK wrote:
> After doing a little test, I believe the oil had been changed before I
> put a deposit on this car.
>
> I had the dealer change the oil and filter and I drove the van around
> for about 15 miles. I then collected some of the oil from the dipstick
> into a glass vial. I repeatedly insert the dipstick into the
> crankcase, withdrew it, and wiped into the glass vial.
>
> The dealer saved some of the original oil in a glass jar.
>
> I also got a sample of the fresh oil, which was Citgo 5W30.
>
> Well, the original oil was very dark and smelled a bit like gasoline.
> The fresh oil was very clear, a bit yellow, and had little scent. The
> oil that had been in the crankcase for 15 miles looked about half as
> dark as the original oil and also smelled a bit like gasoline.
>
> Does this mean anything of significance? I think the previous owner(s)
> ran the car beyond the recommended service intervals (oil & filter
> change) and I believe the fresh oil, with its detergents, is cleaning
> up deposits on engine surfaces.
>
> I will have a compression check run on the front 3 cylinders (the back
> 3 are require removal of the intake plenum).
>
> If I end up buying this one, I will probably change the oil at
> extremely short intervals (~100 miles or weekly) until the oil stays
> clear.
>
>

The "Dark Oil Myth"...

http://www.nordicgroup.us/oil.htm#Th...k%20Oil%20Myth