Good thought... The old oil was mostly 10w30 with a little 10w40
added in. I usually use what ever is cheapest at Wal-Mart or O'Reilly's.
Mixing oils, and weights proves your an Automotive Idiot. Please drive
your car to the nearest salvage yard. Give them the car, and the title in
exchange for a free ride home.
I've never been that concerned with oil & never had a problem.
I've had many vehicles. Except for the Toyota, the GTO's, the Vettes,
and the race cars, they have ALL gone over 225k miles. None of them
ever used any oil between ~4k mile changes. None of them ever had any
problems beyond normal maintenance. None of them ever used synthetic oil.
All were running well when I sold them. The bodies were shot.
The Toyota blew up at 219k miles due to me downshift over-reving
it and throwing a rod. I drove it to the salvage yard on 3 cylinders.
What is wrong with it? Egads! Idiots are everywhere.
Mixing brands alone is dumb. It is ok if you Switch brands, and make
sure you get all the old oil out of the engine. When you mix brands of oil
in a engine, you turn it in to a slot machine. The pay off is rods thru the
What happens? First the different detergent packages are not
compatible. Then second your mixing crude grades. You can mix like grades
(such as Pennsylvania grades, but you can't mix then with say a Texas grade
crude). Mixing Crude grades will just cause sludge, and problems.
As for weights, mixing Multi-Viscosity weight oils is stupid. Not only
do they react to tempitures differently, they will separate in the oil
pan. The thinner oil will sit a top of the thicker (5W30 vs. 10W40) oil.
While your at it you might want to add tome Slick 50 to the mix.
That way you also have 50 weight oil with PTFE floating around to clog your
filter, and bearings. That way you can drop another engine in sooner.
I rather doubt the detergents are incompatible, and as far as mixing
oil from different fields, that may have made some sense a hundred
years ago, but not now.
Um, you do know that the main difference is the various weight are
chemical additives, rather than actually mixing 10 weight and 30 weight
oil, don't you? Otherwise a bottle of 10w30 would have the 10 weight
oil sitting on top of the 30 weight oil. And then when you put the oil
in the engine it would separate out in the engine with the 30 weight
on the bottom and the 10 weight on the top.
Oh, and there are all sorts of things inside the engine to mix it all
up. Like the crankshaft, and oil pump.
Nah, we'll leave that to you, you are the one who seems to have some
strange ideas of reality.
"They that can give up essential liberty to obtain a little temporary
If it doesn't matter, then why are oils rated with types. Not just
weights? Why do some vehicle makers recommend only using certain types?
When they mix your oil at the refinery, they do so in such a manor it
willnot separate. Actually Multi-Viscosity oils are not 2 oils in one
bottle. It is one oil that can thin out. For example 20W50. At 30F try
pouring it. It will be thick as molasses. That same oil at 200F will pour
out like 20 weight.
Mixing 10W30 & 10W40 in your engine will not give you 10W35. In the
warm range it will act as 10 weight. In cold range it will separate, with
the 40 weight laying in the bottom of the pan.
Oils do separate. I have seen it when empting my used oil drum (for
recycling). On the bottom of the drum will be gear oils (such as 80W90),
engine oils will sit in lairs of their own. Such as 5W30, and 20W50.
I have a firm grasp on reality. I know the base oil for slick 50 is 50
weight oil. I also know it has been proven PTFE will cause harm to engines.
It will void warrantees.
PTFE is generic Teflon. Which when added to oil doesn't bond to any
surface in an engine, nor does it provide any extra protection. If you
doubt this, give the good folks at DuPount a call.
The OP said he used what ever was cheapest at two different stores.
Which would mean most name brands, and a few generic brands.
I will not mix different weights of oil in the same engine, no mater
who the maker is. Get me proof from a Chemical engineer it will not harm
the engine, and I still won't do it. Why? Because it would be moronic.
Especially with what people pay me to build engines. Let alone the
stresses some of my race engines see. I don't know, maybe I'm a stick in
the mud. Yet The majority of engines I have had last to well over 300K with
stock bottom ends. The only one that didn't was a Pontiac 301 that was dying
when I got the car.
You obviously do not understand what Multi-viscosity oils are.
I don't spout nonsense. I'm a Professional Mechanic that not only
builds engines & races cars, but builds engines for others. I'm not some
arm chair parts changer who will sit around debating supposed facts. I have
to know what works, and what doesn't. After all my living rides on that.
Now go back to your arm chair.
Yep, but not different types.
Different brand does not mean different type. It only means different
names on the oil. There are standards that oils are supposed to meet.
As long as they meet the standards, then they will work together.
I won't mix weights either. And I won't put generic oil into a good
engine. On the other hand, I have had a couple of cars that were using
quite a bit of oil. Since they were at the end of life for the engine
I would put generic oil in them, but always the same viscosity.
There is simply no reason to mix the weights up. You can get whatever
viscosity you want to begin with.
Actually I do. As a matter fact, I am one of the few who do understand
it. The problem is that you take exactly what I say and reword it.
As I said, a single vis 20 weight will pour easier than a 50 weight
single vis, at any temperature. I should have added one caveat. At
extreme temps they will either be very easy or very hard to pour.
A multi vis oil will flow, and lube, like the lower weight an low temps,
and lube like the higher weight at high temps.
"They that can give up essential liberty to obtain a little temporary
I know some are compatible. It's been so long since I have worried
about that I can't recall. I think it was S-D & S-J that were. Not all
Generic or recycled oils will meet those grading standards.
I did something similar with my old yard cars. When I worked in a
salvage yard. I would pull all the new oil bottles out, separate them by
grades, weights, and such. Then I would use one in one, and another in
another. A few of those had knocking engines, They all were crusher bait
just waiting to die. Not to mention the oil was free. I wasn't going to
tear up my good vehicles out there.
I didn't intend to twist what you were saying. Ill admit I was wrong,
you do know what Multi-viscosity oils are.
Charles, it is pretty clear that you do not know what you are talking about
and at best are repeating ancient urban legends. I'll agree with you that
Slick 50 is a very dumb thing to use, but as to the rest of it you are off
If anyone is interested in more detailed discussion about motor oils, check
out the discussion forums at http://forums.bobistheoilguy.com /. There are
many heated debates there about various issues, but the general level of
knowledge is decades ahead of Charles'.
I had a 1991 Grand Am with a Quad 4. I switched to Mobil 1(full synthetic)
My milage went from 23 to 25. I drove 30 miles each way to work.60 miles a
day, 300 miles a week. It saved me a gallon per week. No big deal right? I
was paying 1.50 for Castrol at that time and 3.50 for Mobil1. I would buy 5
quarts even though it held 4.5. It cost me 17.50 for Mobil1 versus 7.50 for
Castrol. I was down 10 bucks. After using Mobil1 which has a 6000 mile
life(actually recommended up to 12000),I changed oil. It saved me 20 gallons
over the life of the oil change which at that time gas was 1.25. That meant
I saved 25.00 dollars minus the 10.00 difference meant I saved 15.00 plus
you have to add 7.50 more for the second change I would have had to do if I
used regular oil. So it was cheaper. I knew that if my milage went up, my
engine was being better lubricated. That has to mean longer life. I have
been working on cars for a living for 25 years. I was skeptical until I
tried it. I do remember installing Amsoil in peoples cars with carbs 17
years ago and seeing the idle go up. That could only happen with decreased
resistance. If it works out cheaper to use better oil, why not?
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