5-20W oil or 10-40W oil, what's the best for today's tight engines?

5/20W oil flows better in the cold, is 10-40 better for hot weather? The oil is in a 180 degree hold the whole time, except for start up. What should we use?5-20W oil or 10-40W oil, what's the best for today's tight engines?
I live in Texas and it gets pretty hot down here. I use a 10w-30motor oil in all five of my vehicle's. If you would look under your hood , you would see that on most new cars use a 5w - 30 motor oil.There's no need to use a motor oil over a 30 w unless you vehicle's is useing or burning oil , then you might want to use a 40 w motor oil.5-20W oil or 10-40W oil, what's the best for today's tight engines?
5-20 as the oil pump will have to work less to circulate it. Better overall lubrication. Short term the 5-20 for sure. Long term usage before changing and the 10-40 thicker viscosity will hold up better.


The 10-40 will last longer and the 5-20 will give the better short term performance. If you change oil every 3000 miles use 5-20. Personally I would use 5-30
With the new cars of today i would recommend using whatever oil the manufacturer recommends.





The only time i start running different types of oil is when i'm running a pumped up V8. (like a built chevy small block or ???). Thats the only time i change the oils around from break in oil, winter and summer oil.





The new cars may cause damage inside the engine if you dont use the right engine oil.





A friend has a new Porsche 911 that runs 0-40 full synthetic, when he tried 0-30 in it, the top end made all kinds of noise immediately and when he switched back to the recommended stuff it went away...thats just what type it requires to run..





So simply put just run the recommended stuff and that will be the best way to go!





Good luck
In the cold I suggest 0W20 if your car asks for 5/20, the 5 will be more thinner then 5 at start-up. I do not know how many miles you actually have on your car, this has to be taken into consideration. @ 100,000 miles you would now use either 5W30 or 0W30, summer 10 W 30 or even 10W40 and make dam sure you are useing the technical data cleaning for your engine. On the back of all bottles, you will see GM 929 or Ford ww105cc and so forth.
depends on what the engine was designed for.





pick one oil (brand, grade, type) and stick with it.





My Ranger used Motorcraft 5W20 for the 80K miles I owned, and never used or leaked a drop.





Our Jeep Liberty CRD uses Mobil1 0W40, used two quarts the first 5K miles, and has not used or leaked a drop since - now at 55K miles.
the factory usually recommends 5w-30 but you can use 10w-30 also, I would stick with one or the other, in the old days they would use the 10w-40 in the summer but these newer engines don't need that thick of oil.
Whatever the factory recommends. I know of no modern vehicle by the way that recommends 10W40. I find it rather surprising they still make the stuff really. I haven't used any in probably 15 years.
I recommend using the oil specified by the manufacturer. The engine is designed based on tolerance to perform it's best based upon a specific oil viscosity.
I would use what the factory recommends. It will answer your question in the owners manual.