Is there a difference in the weights of motor oil 10/30 and 10/40?

It's the thickness of the oil at temperature. If your truck calls for 10-30 I wouldn't go any thicker because you risk the oil not being able to circulate correctly and you can seize the motor. Here is a more complete definition http://www.driverstechnology.co.uk/oils.htm

The first number is the weight of the oil at 32 degrees and the second number is at 80 or 100 degrees.
The lower the number the thinner the oil.

I have used the standard 10W-30 oil in all my vehicles throughout all seasons, and I personally prefer Quaker or Pennzoil. Buy a middle to top of the line brand. If you happen to have extreme temperature/weather variations where you live, you might want to consider a different weight of oil during those extremes. Most garage mechanics will have their opinion on what weight and brand to use under what conditions and they do a good job of explaining when different types of oil should be used. A Google search for something like "motor oil weight differences" will give you some articles to consider. Try this link: http://www.upmpg.com/tech_articles/motoroil_viscosity/

• Nothing will happen. You should always try to use the same viscosity of oil (5W30) but if your wondering can you put some different weight or brand oil in your engine and it be OK. Yea, it will be fine.

• Hope this helps and thank you for using FixYa.

Regards, Tony

Does it knock hard or just rattle loud,? A lot of cars are noisy till the oil gets pumped up top. I hate to see people floor when they first start up, very bad idea, no oil up top, anyway, your oil weight goes by the outside temperature. If you live in Florida, it gets hot, I use 10w-40 year round, up north is a different story, 5w-30 in the winter would be fine, but summer time you could go heavier no problem. My brother uses straight 30 weight with a bottle of Marvel mystery oil as the 5th qt. The stuff works great. It cleans the inside of your engine like you wouldn't believe. He is one of these guys that takes the oil filters apart to check them out. Hope this helps.

5w 30 or 10w 30 during the winter. After an oil change... check your oil after 200-300 miles of use. Is the level the same? If so your weight is fine. If it drops, it's to light of an oil and your engine is now "drinking it" like fuel, move to a heavier weight. As far as Changing between winter and summer. Changing Oil weights is not bad for your motor so if the winter you go with 5w 30 and it works, great, shoot for the same during the summer. If it seems to "drink it" during the summer using this weight, go up to the next (10w 30)

That being said. Changing from natural oil, to synthetic, back to naturual , or vice versa... swapping back and forth between these KINDS of oil has been known to cause damage. so whatever weight you decide on, stick with one "type", natural or synthetic.

Either one is fine, one is a little thicker.
Then the multigrade motor oil was made.....multi grade means: a different viscosity (thickness)when cold & hot. *Why use a multi grade oil? Because the first number 20w / 10w /5w / 0w is the viscosity of the oil at startup/ cold temperature which lubricates better on start up getting to places the thicker oil wont on startup - when the motor starts to warm up then you have the second number eg. if your oil is a 10w-30 the motor starts up with the oil thinner at 10 weight and as it warms up to operating temperature its thicker to 30 weight. The reason it has thicker oil is to handle the heat etc. Now on a 80Farenheit day / 30 degree C day that thickness may change a bit but it still thinner than the 30 at startup.

HI. The proper weight and type, will be 10W-30.

10W30 should be fine... not sure if you know what those numbers mean... basically cold it will be 10 weight when it warms up 30 weight.... in cold climates that's important for starting the motor.

Robert

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The manuel should tell you what weight of oil to use, IE 10w-30. If you are asking what brand to use, it really does not matter what brand. Many of the different brands are all actually produced from the same company with different labels on them. The laws that oil companies must follow when producing oil are very strict so one brand of oil is not really different from the other. The differences are so small that there would be no noticable affect on your vehicle. It is the same with fuel as well. One brand of fuel is not any different from the other and unless you have a very high performance engine if your vehicle, the difference between low octane and high octane will not be noticable
As far as the type of oil to use, you have oil, partial synthetic oil, and full synthetic oil. Full synthetic is the best.
I would go with full synthetic with what ever the reccomended weight is for your vehicle. Many cars now have what type of weight to use on the oil cap.