Sp33d wrote:i had always thought that the 10w30 was good for the summer while the 5w30 was good for the winter? or was their a 4cyl and a 6 cyl difference between the two?
-Mark
Here is a long explaination (please bair with me Bro

)... It really depends on the cilmate you live in where excessive heat is present (for example constant 110+ degree weather). This extreme heat quickly breaks down the viscosity of the oil. Thick oil is not always good for an engine. Yes, the thicker oil will provide a thicker layer of protect for the walls of the combustion chamber; however, if the oil is of a lower viscosity (standard mineral oil) it tends to gum up the valves with sludge, varnish and carbon build-up. It also puts stress on the oil pump. With all these stress conbined, they make the engine work harder due to more resistance. This transilates to more fuel consumption (poor fuel economy)... Some mechanic use the thicker oil in worry that the thinner oil will seep through the head gaskets; therefore, they use the thicker oil to keep it from leaking out...... It really depends in the area you live in and is souly the owners free will.... Hopefully this info is helpfull
Peace,
-G