Oil Weight Question?

[stagger_lee]

This is a dumb question, but I have never got a straight answer. I just did my first oil change this weekend. Used Mobil 1 5W -30. I read in the manual the H3s require 5W 30 only. What are the pros and cons of using a heavier weight? Why do they say to only use that specific weight oil? Thanks all!

[graydog]

Originally Posted by fagger_lee

This is a dumb question, but I have never got a straight answer. I just did my first oil change this weekend. Used Mobil 1 5W -30. I read in the manual the H3s require 5W 30 only. What are the pros and cons of using a heavier weight? Why do they say to only use that specific weight oil? Thanks all!

You are correct, that is a dumb question.

[DRTYFN]

Learn to use the SEARCH feature. And pay attention to F5's advice.
http://www.elcovaforums.com/forums/s...ight=oil+5w-30

[stagger_lee]

Originally Posted by DRTYFN

Learn to use the SEARCH feature. And pay attention to F5's advice.
http://www.elcovaforums.com/forums/s...ight=oil+5w-30

Yeah I did SEARCH and read all that, I understand differences between Synthetic and Non, but question was directed to weight, those differences, pros and cons of heavier weight oil, were not explained. Just curious.

Graydouche

[Desert Dan]

Most new engines are using lower viscosity multi weight oils like 5-30wt.

I am not sure why? That would be an F5 question
Maybe higher tolerances require thinner oils or the 5-30wt lubricates better?

What about in extreame heat 110 degrees plus is the 5-30 good enough?

[stagger_lee]

My exact questions, when to use heavier weight and why?

[graydog]

Originally Posted by fagger_lee

My exact questions, when to use heavier weight and why?

ITS over your head dude just drop it.

[Vettster]

Originally Posted by Desert Dan

Most new engines are using lower viscosity multi weight oils like 5-30wt.

I am not sure why? That would be an F5 question
Maybe higher tolerances require thinner oils or the 5-30wt lubricates better?

What about in extreame heat 110 degrees plus is the 5-30 good enough?

Part of the reason is for fuel savings.
Living where I do, I always use heavier oil.
Mobil 1, 15-40 or so.

[f5fstop]

The 5W is used for energy conservation during cold engine operation. A lower weight also allows for oil to flow up to the top of the engine more efficiently in cold weather. The 30W is the maximum GM recommends for any gas engine they now manufacture (the Honda engine in the VUE required 5w20).
These requirements are per SAE, and it means in cold temps, the oil will flow like a 5W, as the engine warms up it will flow like a 30W. Some type of index viscosity additive is used to make this all happen.

Using 40W in ANY modern GM engine will most likely cut its life span. In addition, I don't believe any 40W or greater oil passes GM's required spec for the H3 engine. If you ever have a major internal engine problem, and a GM field rep gets curious, he/she may send a sample out for testing. In two days, they can tell what oil is in the engine.

What oil you should use will be debated until the end of time, just like when to change your oil and which is better Chevy or Ford trucks. So, I'm just telling you what GM requires, that is in writing in the owner's manual, and to understand, using this recommended oil WILL not cause engine problems. I always have used 5W-30 in my Vettes and lived in the south, and had no problems.

[stagger_lee]

That makes sense. Good thing I obeyed the requirements. So would you say that a heavier weight would work better in hotter running engines, ie: aircooled VWs and porsches, diesels, hot rods running high compression and forced induction, etc.?

Thanks for the info F5.

[deserth3]

No. It has to do with engine tolerances. In older engines when they start to burn excessive amaounts of oil people would put in a heavier weight to put off rebuilding the engine.
The heavier oil would not pass between the cylinder walls and rings.

Frequent cold starts/cold engines running heavier oil will show more wear over time.

[Huck BB62]

Thicker oil will cause you a mileage drop. There's alot going on with the oil. It not only lubricates (a lot of people actually think that oil's primary job is to be slippery), it acts as a medium to carry the heat away and acts as a hydraulic fluid. A thicker oil takes horsepower to pump and for the parts to move around in it. Try stirring a spoon in water, then stir it in honey. That's an exaggeration, but that's the general idea. Thicker oil will NOT make your engine run cooler. A thinner oil actually gets rid of heat easier. It takes the heat from the engine part faster and transfers it to the cooler easier. This is because laminar flows. The higher the viscosity of an oil, the thicker the laminar flow is and the heat transfer is not as efficient. Laminar flow is the dead area of fluid adjacent to whatever it's flowing against.

The new engines run great with 30 weight oil. The tolerances are much closer, the oil is much better. Thicker oil thinking is of the past.

The engineers actually take into account the tolerances, the rpms, and other parameters of the engine design when they spec the oil for the engine. Following the recommendation is a what we should do.

The viscosity improvers that change it from a viscosity of 5 when cold to a 30 weight when warm are actually long chain polymers that coil and uncoil at different temperatures. When these break down, this is why your oil drains like water when the oil's old.

Using thicker oil is particularly bad for your engine when the engine is cold. It doesn't get pumped to the top end as quickly as a multi viscosity of the proper viscosity. At the very worst scenario, a bearing could be damaged because the oil wedge that a journal bearing is designed for (again depending on the bearing clearance and rpm) may not be proper when a thick oil is used actually causing bearing damage. (revving your engine when it's cold is a sin for this very reason) This is also one of the merits of a synthetic oil, it's pour point at cold start is far superior to any mineral based motor oil.

Stay with the 5W-30, better yet, get one of the good synthetics (my favorite flavor is Royal Purple) they're all superior to mineral based.

I follow the GM oil monitor. I'm getting almost 10k between oil changes so the cost for a premium synthetic oil and oil filter (Mobil 1 M1-206 is the correct critter for the job) is not worth worrying about for the extra protection offered. Changing the oil any sooner is a waste of resources.

[evldave]

Originally Posted by Huck BB62

Thicker oil will cause you a mileage drop. There's alot going on with the oil. It not only lubricates (a lot of people actually think that oil's primary job is to be slippery), it acts as a medium to carry the heat away and acts as a hydraulic fluid. A thicker oil takes horsepower to pump and for the parts to move around in it. Try stirring a spoon in water, then stir it in honey. That's an exaggeration, but that's the general idea. Thicker oil will NOT make your engine run cooler. A thinner oil actually gets rid of heat easier. It takes the heat from the engine part faster and transfers it to the cooler easier. This is because laminar flows. The higher the viscosity of an oil, the thicker the laminar flow is and the heat transfer is not as efficient. Laminar flow is the dead area of fluid adjacent to whatever it's flowing against.

The new engines run great with 30 weight oil. The tolerances are much closer, the oil is much better. Thicker oil thinking is of the past.

The engineers actually take into account the tolerances, the rpms, and other parameters of the engine design when they spec the oil for the engine. Following the recommendation is a what we should do.

The viscosity improvers that change it from a viscosity of 5 when cold to a 30 weight when warm are actually long chain polymers that coil and uncoil at different temperatures. When these break down, this is why your oil drains like water when the oil's old.

Using thicker oil is particularly bad for your engine when the engine is cold. It doesn't get pumped to the top end as quickly as a multi viscosity of the proper viscosity. At the very worst scenario, a bearing could be damaged because the oil wedge that a journal bearing is designed for (again depending on the bearing clearance and rpm) may not be proper when a thick oil is used actually causing bearing damage. (revving your engine when it's cold is a sin for this very reason) This is also one of the merits of a synthetic oil, it's pour point at cold start is far superior to any mineral based motor oil.

Stay with the 5W-30, better yet, get one of the good synthetics (my favorite flavor is Royal Purple) they're all superior to mineral based.

I follow the GM oil monitor. I'm getting almost 10k between oil changes so the cost for a premium synthetic oil and oil filter (Mobil 1 M1-206 is the correct critter for the job) is not worth worrying about for the extra protection offered. Changing the oil any sooner is a waste of resources.

I can't speak to the rest (it sounds reasonable), but Laminar Flow is actually the smooth flowing part in the middle of a stream of viscous fluid (whether it be oil or water or urine). The edge has many terms (boundary layer is one), but to clarify the Laminar Flow is the smooth flowing portion in the middle of the stream. (sorry, I spent years doing hydrology can't let a you get away with using incorrect terms)

[stagger_lee]

Thats what I was looking for. Thanks all! You guys are awesome!

[Huck BB62]

Originally Posted by evldave

I can't speak to the rest (it sounds reasonable), but Laminar Flow is actually the smooth flowing part in the middle of a stream of viscous fluid (whether it be oil or water or urine). The edge has many terms (boundary layer is one), but to clarify the Laminar Flow is the smooth flowing portion in the middle of the stream. (sorry, I spent years doing hydrology can't let a you get away with using incorrect terms)

Arrrgghhh, I quite agree as the term concerns hydrology, but not as the term is used in fluid systems. Laminar by it's very definition is "layers". In the context of a viscous fluid, lube oil, through a pipe or over a machined part, the term laminar is used thusly:

Consider the flow of oil as it passes a pipe's surface. The boundary layer is a very thin sheet of oil (as I explained earlier it's thicker as the oil's viscosity is increased) lying over the surface of the pipe, metal part, and anywhere the oil flows with velocity past a surface. Because oil has viscosity, this layer of oil tends to adhere to the pipe. As the oil moves past the pipe, the boundary layer at first flows smoothly over the relatively smooth surface of the pipe. Here the flow is called laminar and the boundary layer is a laminar boundary layer (this is where I incompletely used the term laminar).

As viscosity, or velocity of the oil is increased, this laminar layer or stagnantly thick layer of oil is increased, thusly hampering heat transfer due to the friction of the part against the flow of the oil itself.

The point at which the boundary layer changes from laminar to turbulent is called the transistion point. Where the boundary layer becomes turbulent, drag, due to friction, is relatively high.

This same exact usage of the laminar region is utilized in air craft design.

It's why a golf ball has dimples, to break up the laminar flow of air over the ball. A perfectly smooth golf ball goes only a fraction of the distance as a dimpled ball.

As oil applies to the inside of your engine and the reason higher viscosities can spell trouble:

http://www.cartage.org.lb/en/themes/...daryLayers.htm


I apologize for any confusion I may have caused. evldave is fundamentally correct.

Now we're all learned on it!

(I'm a certified tribologist, shame on me for not explaining it properly)

[HummBebe]

tri?bol?o?gy play_w("T0346400&quot (tr-bl-j, trb-) n. The science of the mechanisms of friction, lubrication, and wear of interacting surfaces that are in relative motion.

For those of us who couldn't remember tribology.

Originally Posted by HummBebe

For those of us who couldn't remember tribology.

Nice, learned something today.

[stagger_lee]

Very informative thread.

Thats funny I guess I am and amatuer tribologist considering I definately know all about the science of friction, lubriction and interacting surfaces of movement. I always had considered myself better called an amatuer gynocologist, but tribologist will work.

[evldave]

Originally Posted by stagger_lee

Very informative thread.

Thats funny I guess I am and amatuer tribologist considering I definately know all about the science of friction, lubriction and interacting surfaces of movement. I always had considered myself better called an amatuer gynocologist, but tribologist will work.

Would that make you a try-balls-ogist?