Ummm...no.

Let me try this.
10W-30 oil will behave like:

At 0C like 10 weight at 0C.

At 100C like 30 weight at 100C.

It will thin when hot, but no more that the higher weight will be at the same tempature. SAE10 at 0 is like oil, but at 100 is more like water, where as SAE30 at 0 is like molasses, at 100 is like oil. Thus is the benifits of mulitvis oils. We are saying the same general thing...just differentlly. Cold oil is thicker than hot, a higher number oil is thicker than a lower.

And I agree....if your engine burns oil...fix it...a thicker oil is not a fix.

Rev

 

Your example still assumes that the 10W oil will become the same viscocity as a 30W at a given temp. That simply is not the case. But I dig what you're saying though.

 

TRUE!!! Even factories make errors!!!!!!!!!!!!!!!!!

 

AMEN. Could'nt have said it any better!!!!!!!!!!

 

I appreciate everyones input. But now I'm really confused. I used to run 20W-50 racing synthetic in my tricked out 5.0 Mustang. That was 15 years ago. Heck, I remember running straight 30 weight in my f-100 pickup. These newer engines kinda scare me when it comes to tolerances, over head valves, modular designs, plastic intake manifolds, etc. I think I'll stick with what the manual says.

5W-30 Mobil 1 is what I'm gonna use.

Thanks for your input.

Jeff

 

Another explanation from Amsoil website:

Multi viscosity oils work like this: Polymers are added to a light base (5W, 10W, 20W), which prevent the oil from thinning as much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.

 

Well said. Now after reading that, do any of you REALLY want to use 5W oil? Shoot! That explanation now has me leaning towards a 20W base.

 

I'm apparently in the minority, but I've got 91K miles on my 2001 X and have used nothing but the Motorcraft 5W-20. I, nor anyone else will likely ever know whether other choices would have been better.... or worse.

Joe

 

No....but 5W-30 will work just fine for me. Thin when cold....I like that, so does my engine.

Rev

 

Owners Manual's do have mistakes sometimes, But I have used the weight specified in them for 26 years with no problems yet?? I use Mobil 1 in some and Valvoline Synthetic in others. What type I first use in each vehicle is what stays in each. I change oil and Filter every 3000 miles or 4 months.I use Motorcraft oil fiters in Fords and Mopar oil filters in Mopars.
69 Road Runner-Restored 1300 miles
71 Road Runner-Restored 1100 miles
73 F-150 2 Wheel Drive 264000 miles
85 F-150 4 Wheel Drive 144000 miles
87 T-Bird Turbo Coupe 79000 miles
99 Dodge Stratus 107000 miles

 

Ive run the factory recommended 5w20 since new and have had a little trouble finding it at times. I had the truck at the dealer for a warranty issue and had them do a oil, filter and lube. When I got the truck home I checked the stick and it was low. The dealer changed the oil and filter and installed 5 quarts in my v10. I brought it back to them immediately and they were caught by me putting 10w40 in the truck. I immediately complained about it and forced them to dump it and find the right stuff. Then a day later i was under the truck and found out they never greased anything and all the grease fittings were still dirty. Went back to the dealer and they told me that there were no grease fittings to grease. Since I had greased the truck previously I knew there were. I had it put on the rack and started pointing them out. Dealer was Lynch Ford in Chicago. I suggest you never go there. (I only went there cause its 4 blocks from home and I could walk home. Bill

 

I do all work on all my cars and trucks. Only items I let any body do is front end alignment and mounting tires on rims. I put the rims and tires on the autos myself. Most Dealers and Garages I have seen are under so much stress (the workers),and are rushed by owners and/or boses, that quite a few repairs are not done the way they should be. I started doing auto work at home for friends and neighbors, and have enough business to open my own garage, which I'm in the process of trying to do now.. I built trust in my customers by giving them great work at a great price and not ripping any one off.

 

Here's something that will help explain the viscosity and grades.

Engine oil grades
As long ago as 1911 the Society of Automotive Engineers recognized a need for standardizing grades of oil for automobile engines. Today the ratings are provided in collaboration with the ASTM and the American Petroleum Institute (API).

In the United States, engine oil ratings are indicated by a trademarked circular design on the package. The mark contains three pieces of information. In the inner circle is a viscosity grade. In the upper part of the outer circle is an API Service Classification, and the bottom of the outer circle may contain an energy conservation rating.

The package may also have a starburst symbol. The presence of this symbol indicates that the oil meets standards set by the International Lubricant Standardization and Approval Committee, whose members represent American and Japanese automobile manufacturers.

Viscosity
The purpose of the viscosity rating is to assure that, in the climate in which the engine is operated, the oil will always be able to flow through the engine's lubrication system. Eleven grades are defined. Six of them end in the letter “W,” beginning with “0W” and proceeding in steps of 5 to “25W.” The W stands for winter. The remaining five grades go from “20” to “60” in steps of 10, without the W. In general, higher numbers mean higher viscosities.

The viscosity of the oil is tested at 100°C. Its viscosity must be greater than a minimum that is specified for each grade. For the grades without a W, a maximum viscosity is also specified. This test basically ensures the oil will perform in a warm, running engine.

For grades ending in W, in addition to the minimum viscosity at 100°C test, a low temperature test is required. The temperature depends on the grade; for the 0W grade it is 35°C , for example. The purpose of the low temperature test is to ensure that if the oil's viscosity is low enough to permit cranking, it will also be low enough to be pumped through the engine. (Those processes involve different kinds of viscosity, so the cranking viscosity is measured in centipoises and the pumpability viscosity in centistokes.) The test temperatures rise by 5°C for each grade; oils with the lower numbers are intended for climates with colder winters. However, to select a viscosity grade for a particular car, consult the owner's manual and not just an outdoor thermometer.

Multiviscosity oils, such as “20W–50,” must satisfy both the low temperature cranking and pumping test for the grade indicated first, and the 100°C test for the second grade. Such an oil would also pass the tests for all the grades in between.

Service classification
The original grades were based only on viscosity. In 1947, three service classifications were added:

Regular, which was straight mineral oil
Premium, which had added anti-oxidants
Heavy Duty, with anti-oxidants and detergents
Both engines and the technology of lubrication became increasingly more sophisticated, so these classifications were replaced in 1952 with:

ML, MM, and MS classifications, in order of increasing quality, for oil for gasoline engines
DG, DM, and DS, in order of increasing quality, for diesel engines
After a number of revisions, those classifications were replaced by an entirely new, more easily extended system in 1983.

For gasoline engines, service classifications start with SA and proceed through (so far) SJ. Classifications SA through SF are considered obsolete, except that SE and SF are needed for certain smog systems which can be poisoned by additives present in later classifications. SA has no requirements at all; while the others are for earlier generations of engine (SC, 1964; SD, 1968; SE, 1972; SF, 1980; SG, 1989; SH, ; SJ, 1996). SJ is suited to a 1996 engine.

A similar set of classifications covers diesel engines. CA, CB, and CC are obsolete; CD, CD-II, and CE are in current use.

Hope that helps,