oil change!

1990 sundance 2.5

whoops...so I picked up castrol 10w30 today...except that the three quarts
behind the first one at the store were 20w50....and i only noticed after i
changed the oil

how bad will it be if I run my car now? Even to drive to the auto parts
store and get the better stuff? Is it undriveable with 1qt 10w30 and 3qts
20w50?

-sachin

 

Don't even worry about it. All you basically did is raise the base
viscosity a small amount. Mathemattically you now have 12.5W30 in there.
Just put the whole thing out of your head and drive the car until the next
regularly scheduled oil change. Only next time check all the bottles first.

A 1990 vehicle most likely has enough miles on it to have worn the bearing
clearances a little so the microscopically thicker oil might even be a plus.
The 30 and the 50 part of the oil rating has nothing to do with the actual
viscosity.

Absolutely nothing to worry about.

--
Mike....................................................
"Opportunities are spawned from crisis"
1990 sundance 2.5

whoops...so I picked up castrol 10w30 today...except that the three quarts
behind the first one at the store were 20w50....and i only noticed after i
changed the oil

how bad will it be if I run my car now? Even to drive to the auto parts
store and get the better stuff? Is it undriveable with 1qt 10w30 and 3qts
20w50?

-sachin

 

Don't even worry about it. All you basically did is raise the base

Actually...with one quart of SAE10 and three quarts of SAE20, wouldn't I
have 17.5w oil in there?

 

Wrong. More like a 17.5W45.

Wrong again. The first number describes the behavior of the oil when
cold and the second number describes the behavior of the oil when hot.

I agree that I wouldn't worry too much about it as it likely won't cause
any trouble other than slower cranking when starting and a probably
imperceptible loss in mileage. I would worry though about the answers
Rufus gave.

If you want correct information, here's one place to check out:
http://www.texacoxpresslube.com/carcare/article_viscosity.html

Matt

 

Hold on a minute. re: my math error - I misread it as 3 of 10W and 1 of 20W
so an honest mistake and you are correct.

BUT the first number is the oils SAE viscosity as indicated in a standard
Saybolt Universal viscosity test. The flow time is converted to the SAE
number.

The second number does NOT mean the stuff turns into 30 or 50 W when hot.
This is chemically impossible at the temps engine oil runs at. What it DOES
indicate is that it acts similar to 30 or 50W at a specified temp due to the
additive package. Meaning it has breakdown and load bearing properties of
the larger number. Heat up 10W30 to 200 degrees and heat up 10W to 200
degrees and run them through a Saybolt Universal orifice and they will flow
exactly the same. This is because they are both SAE10 viscosity!

Before you go blasting someone you ought to really have all the facts
straight. It must be wonderful to have gone through life and never made a
mistake.
--
Mike....................................................
"Opportunities are spawned from crisis"

first.

Wrong. More like a 17.5W45.

Wrong again. The first number describes the behavior of the oil when
cold and the second number describes the behavior of the oil when hot.

I agree that I wouldn't worry too much about it as it likely won't cause
any trouble other than slower cranking when starting and a probably
imperceptible loss in mileage. I would worry though about the answers
Rufus gave.

If you want correct information, here's one place to check out:
http://www.texacoxpresslube.com/carcare/article_viscosity.html

Matt

 

It was obvious what you had done and that is why I included the smiley
at the end. I was having some fun with you.

I never said it did.

I don't think this is correct. Every source I found, including the one
listed below written by an engineer at Texaco says otherwise.

I believe my facts are straight, and I provided a credible source to
support what I said. Can you provide a source to support your assertion
that a 10W30 oil performs the same as a 10 weight oil at high
temperature rather than like a 30 weight oil which is what I believe is
true and what every source I've read says is true?

I never said I've never made a mistake, I simply pointed out several
mistakes in your first post. Unfortunately, it appears you still are
making at least one mistake persistently. No offense, but I trust the
engineers at oil companies more than I trust someone on a newsgroup when
it comes to the topic of oil.


Matt

 

I think you meant to say "Heat up 10W30 to 200 degrees and heat up 30W
to 200
degrees and run them through a Saybolt Universal orifice and they will
flow
exactly the same. This is because (at that temperature) they are both
SAE30 viscosity!".

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

Unfortunately, Bill, I think he really meant what he wrote.


Matt

 

These websites will give you most of what you ever need to know about motor
oil

http://www.bestchoice-car-care.com/car-oil-change.html
http://www.1st-in-synthetics.com/oil_additives.htm
http://www.xs11.com/stories/croil96.shtml ..

 

Yes, a nice overall summary, but sounds a little like an Amsoil
commercial at the end with the 25,000 mile oil change comment/link.

OK, I knew it was coming after the first link. Take this with a big
grain of salt.

I read this when it was first published in CR, but it is meaningless for
the type of driving that I do. All if proves is that taxi companies can
change their oil every 6,000 miles. I disagree with CR that this is a
severe test in many ways. Cold starts in cold weather are very hard on
engines and oil. Running short trips where the engine never gets warm
enough to burn off the moisture is much more severe than idling in a
taxi. I could go on. Also, 60,000 miles is just past break-in for most
modern engines so measuring wear at such a low mileage is also pretty
much meaningless. If you operate a taxi, this is a great test. If you
don't, then it is next to useless for you. I use Mobil 1 for its cold
weather performance primarily. This test completely ignores that. The
report comments on it briefly, but the test doesn't cover this regime.


Matt

 

I had a better site than those but can't find it.. while none of them can be
seen as definitive, they do show that no matter who you ask, you will always
get a slightly different answer.. it does really come down to driving
conditions and style, and in that respect we are all different.. in this
part of Canada (eastern Ontario) the wildly varying temperature change from
high summer to 'damn cold' winter makes people change oil regularly
regardless of what others might tell them..

 

We have a similar problem in northern PA, which is why I use Mobil 1
5W30. It works year round from -30F to 100F+.


Matt

 

lol.. -30F up here is considered a heat wave at times.. have seen the
thermometer drop to -45.. fortunately, it does not happen too often, apart
from this year..

 

We only hit -30F about once a decade or so, but I like my car to start
and lubricate well even on those rare occasions. Our coldest this year
was -20. Even at -45F, synthetic is a lot better than dino oil,
although probably still too viscous without a block heater.


Matt

 

The previous owner of my Jeep failed to take the option of a block heater,
and I have been feeling cheap for a while now.. but I do have a block heater
ready to be fitted,, it is a cute little thing too.. seems a shame to spoil
it by fitting into the block.. I have a Jeep 'Thermoguard' battery wrap
too.. still in its box as it is way to cold to go out and fit it.. needless
to say, the Jeep has started up every morning anyway.. the thermometer reads
+3c so I may just do it this morning..

 

Depends how cold it is. At -30 it won't start. At 50F no problem at
all.