+1000.it is a myth that you cannot change back and forth between standard, synthetics, and blends.
It is actually one of the more popular myths, but it is not correct.
Recommended is 10W-40. If your oil is seeing temperatures in excess of 248degF / 120degC due to mods and track use etc then there is a strong argument to using an SAE 50, as it will have more viscosity at these excessive temperatures. If your oil temp does not exceed 120degC at any time then a good "shear stable" SAE 40 is perfectly capable of giving protection. Thicker oils cause more friction and therefore more heat and they waste power and affect fuel consumption so it's always best to use the thinnest oil that you can get away with and still maintain oil pressure.
hey everyone .... first post
the first number is the weight of the oil cold ... the second number is how well the oil protects at operating temperature. For example, 10-40 is a 10 weight oil that protects like a 40 weight oil at operating temperature.
Essentially, at operating temperature, 10-40 oil protects from wear exactly like a 40SAE oil ..... but with the 10-40 oil having the benefit of flowing like a 10SAE oil when cold.
Craig
REALLY? ???...Actually the W stands for Winter Not Weight