20w is a thicker oil it has a higherfreeze point 30w has a lower freeze point

 

The weight of the oil has nothing to do with the freeze point. 30 weight is thicker than 20 weight but not enough to make a difference so it's ok to use. The first number before the W is the point where the oil gets really stiff. Example: 5W-30 means -5 Winter so the oil doesn't start getting hard until then. The second number is the weight and the higher the number the thicker the oil is.

 

folks, w mean weather, not weight, water, wamu, nothing, it means weather. The first number relates its viscosity at start up(cold weather), the second number represents its viscosity at operating temperature. We have multi viscosity oil for the simple reason of cold climates. They need the oil to be thin when its cold so it can quickly get to all the places its needs to go. If it was thick, it would starve the valvetrain of oil and cause damage.

You can use 5w30, 10w30, 5w20, 0w-20, 0w-30

 

also in ford v8s in 2001 is when they changed to 5w-20, for fuel consumption. They beleive the thinner oil will reduce fricition, getting you better fuel economy, almost all hondas and what not say 5w20

 

The "W" is for Winter, and when used with multigrade oils it means that the oil will pump as well as a straight "whatever" grade at low temperatures (I.e. 5W-29 oil will pump as well at low temperatures as a straight 5W motor oil). The second grading number indicates that the viscosity of the multigrade oil will be more or less that same as a same-weighted straight oil at 100°C (212°F).[/align][/align]So, 5W-20 will pump as well as plain ol' 5W (SAE 5 weight, Winter rated) at low temps, and will have the same viscoity as straight 20 weight oil at 212°.[/align][/align]Here in Florida I can't bring myself to put 5W-20 in anything, so I run 10W-30 synthetic in my 2003 GT, and 20W-50 Valvoline MaxLife in our other higher mileage cars--when the GT gets up to 100k or so it will probably be living on 20W-50 as well...[/align]

 

I have had numerous petrol engineers, and corporate faces for oil companies, ie conoco phillips, exxon mobil, etc tell me that the W stands for weather

 

A guy that works for exxon mobil is at my work right now and he said that it stands for weather, but has nothing to do with its conotation.

 

VT and Liver(anoyance) says 5-30 but manufactures say 5-20. Chemestry says 5-20 has smaller molocules that wet-soak the surfaces better than the larger molocule 5-30. It may or may not make a difference honestly. Just make sure it's synthetic..

 

In over 50 years of buying oil I've never heard of the "W" being referenced as "Weather" (it doesn't makes sense, 105° in the shade is "Weather")...[/align][/align]The SAE J300 spec(they're the one's that made it up) says it stands for Winter...[/align][/align][/align][/align]

 

w stands for winter, in the basics class at uti they pound that into your head. i run 10w30 amsoil in my car.