Some new German cars, such as Porsche, specify 0W-40 (synthetic). Many Japanese cars specify 0W-20. For Yamaha golf carts, 0W-30, 5W-30, or 10W-30 are all OK. The second number, essentially the viscosity at operating temperature, is the important number. Buy whatever is on sale and change it according to the owner’s manual recommendation. I tend to buy Mobil-1 (synthetic) because I can get it for about $3 a quart after rebate.
Quote:
Originally Posted by Win1894
I would never consider using a 10W-40 oil in this age of synthetic oils. A quality full synthetic 0W-30 or 5W-30 will give you excellent start-up protection and once at operating temperature, excellent flow for cooling and extended wear protection. Today's 30 viscosity synthetics have much better high temperature shear strength than a conventional 40 viscosity oil. The only reason a 10W-30 oil exists is becasue they, before synthetic oil chemistry, couldn't easily make a 5W-30 oil. The only reason you can still buy a 10W-40 oil is because there are still some really old engines around whose manufacturers at the time recommended it. There is no good technical reason to use it.
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