Semi-Syn oil = mpg increase

Charles Bendig wrote in alt.autos.gm

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.

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. Charles

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 the wall.

If anyone is interested in more detailed discussion about motor oils, check out the discussion forums at

There aremany heated debates there about various issues, but the general level ofknowledge is decades ahead of Charles'. John

Less cars on the road definitely could be a factor. Uuuhg, don't ya just hate getting stuck behind those school buses?

What K&N bullshit was that?

I fell for that slick 50 bit once a long time ago. NEVER again!

Back in the days when Googleplex was the chief troll fighter in alt.autos.camaro.firebird (aacf). Little Stevie would come in and post a B.S. Story about using K&N filters in Mining Equipment (such as haul trucks, and converiors).

Concerned that some idiot was telling people a K&N filter would cause there engines to expire, I forwarded a copy to K&N. I also put a Call in to a cousin of mine that at the time worked for Fletcher Mining Equipment. He was in R&D there (Two of his sons still work there today doing the same jobs he did at the time).

Both K&N and Mining Equipment Manufactures DO NOT recommend K&N, or similar cleanable air filters for use around mines.

Thus proving that if he actually did so, Little Stevie was an Idiot first class. Charles

Charles Bendig wrote in alt.autos.gm

We're not really talking about different types of oils, are we? We are talking about different brands an weights.

That is what I said. 20 weight will pour easier than 50 weight at any temperature.

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You are the one who is spouting nonsense, I have no idea why you seem to doubt the snake oil.

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. Charles

Charles Bendig wrote in alt.autos.gm

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.

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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.

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