5W-xx vs 10W-30 Oil

[shogun32]

Modern polymers are less fragile that is true. But I personally think 10w is fine for any use that isn't below 25f.

But the use of W numbers is pointless. What matters is cst@0 and 100c

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[thunderstrike]

Everyone -- very good points.

What concerns me is this when changing oil -- seeing the used oil drain like water with no viscosity remaining. When Mustang GT's oil drains out the large water-hose diameter, gushing out with little to no viscosity one wonders about the oil weight each time.

 

[Paul McWhiskey]

All engine oils are base oil + an additive package. True, the higher he quality of the base oil the less additives "might" be needed. The engine producers develop an oil specification for their engines and the oil producers develop a product to "meet" that specification. that does not mean that all of the oil producers develop the same product. Base oil is relatively cheap compared to the additives. There are viscosity improvers, several different detergents, defoamers, and seal swell agents just to name a few of the many, many that are needed and available to produce a finished product. As I mentioned they are all quite expensive. So part of the decision-making process when developing an oil to meet manufacturer XYZ's specification is not just what to use, but which and how much to use in order to reach a price point that is acceptable to the manufacturer and the public. So, with specs becoming more and more demanding the oil companies have had to seek new and different additives to control cost in addition to meeting the spec. For instance, in order to meet the 5W20 specification for Ford Motor Company it was necessary to add some synthetic base oil to conventional base oil. How much? There is no regulation on that. It could be as little as just a few drops in a quart. When Ford Motor Company decides who's oil they are going to buy for factory fill, guess what, it goes out to bid. They buy the cheapest oil from a reputable company that "meets" their spec. It is not the wonder lube that has been on a Mars expedition, it is a quality product that does what they need it to do at the best price they can get. With specifications changing so often nowadays due to having to meet EPA pollution requirements and CAFE standards the oil producers see no benefit in formulating robust products that exceed the spec as they did in times past. The reason is that it costs many millions of dollars to formulate, test, and receive approvals for each product that they produce. So if the spec is going to change in 2.3.4 years, they have to spend all of those millions again, so there is no motivation to super exceed spec. It can be done, but why would they? Leave that to the "Boutique" producers and let them spend their money on marketing and sales. I will name two here Redline (bought out by Conoco Phillips) and Amsoil. Are they better products? You decide.
Just to track back to Motorcraft oil for a moment, Before I retired four years ago Conoco Phillips had the contract for Fords factory fill. It is nothing special, it is the same product that is in a Phillips 66 or a Kendall bottle.
As to viscosity grades a 5W oil is 5 weight (which is actually a measure of viscosity in Cst and has nothing to do with how much it weighs) at low temperatures. The number that follows is the viscosity of the oil and with very little variance from brand to brand a 30 weight is a 30 weight as are all of the other viscosities. Generally speaking the lower the viscosity of an engine oil the faster it will pump to moving parts in the engine (pumpability, another aspect of lubrication). this is important if you live in colder climates as most engine wear happens at start up. If you live in Fairbanks this is very important. If you live in Phoenix, it is nearly meaningless. As to changing from a 5W20 to a 10W30? Where do you live? Not saying that it is the most important part of choosing, but what is the pumpability difference between the two when your lowest temperature is 40 degrees? I will tell you not much. I know of shops who use 15W40 Heavy Duty Diesel engine oil in every piece of equipment that they have. Why? Because they do not want to inventory 15 different products. They may use manufacturer spec oils until the warranty is out and that is it.
I could go one here, but let me say this, use whatever you believe or have experience with that makes you feel you are getting what you demand from your machine. Notice that I have not said that Brand XYZ is the penultimate lubricant and if you don't use it you are leaving longevity or power on the table. And, with that said I will tell you that there are products available that outperform others. And trust me, if you want them you have to pay for them. Don't ever believe that there is a company out there that is going to provide the most amazing anything that outperforms everything for the Dollar Store price.
If it does what you want and you can afford it then buy it. Beware of everything that is incredibly cheap (I have seen the destruction that saving $1.00/gal on oil can do). Spec Sheets and Data Sheets are wonderful, just like oil analysis, IF you know how to read them. and always remember that everyone has an opinion. And they are guaranteed the ability to spread it by the 1st Amendment. The onus is on you to do your homework, seek out the knowledge, listen to the ones that know what they are talking about (like some here on 6G), and make the best decision for your application.

 

[thunderstrike]

Thanks for the great info. Will probably go back to 5W-30 next change.

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