confused? you will be.
What do those numbers mean?
The number designation found on an oil container represents an oil's viscosity rating. Viscosity is a measure of the oil's thickness. Oil viscosity numbers are assigned to the oil by the S.A.E. (Society of Automotive Engineers). The "W" rating means the oil has been rated for winter use and that the oil meets specifications for viscosity at 0 degrees Fahrenheit. Using accepted techniques, measurements are taken at specific temperatures to measure the oil's viscosity number. Oil with too low of viscosity can breakdown and lose strength at high temperatures. Oils with too high a viscosity may not pump through the engine quick enough to lubricate engine components properly at low temperatures. Engine oil should flow easily when the engine is cold and remain thick enough to protect the engine when the oil is hot. The two types of oil viscosities are single viscosity or straight-weight oils, and multi-viscosity or multi-weight oils. Single weight oils are oils that do not change in viscosity. For example, 20-weight oil would remain 20-weight oil at all temperatures, where as 10-30 would be 10-weight oil when cold and 30-weight oil once warmed to normal engine operating temperatures. Look at the lowest temperatures you will encounter in winter driving and the highest temperatures you will encounter in summer driving and base your selection on that range. The wider the viscosity spread the greater the use of polymers to achieve that viscosity spread. Polymers can break down and form deposits that can increase engine wear and decrease engine life so, generally speaking, the lower the viscosity spread the more durable the oil will be. Remember to use multi-viscosity oils with the smallest viscosity spread you can get away with for the temperature range in which the vehicle will operate.
After digesting all that. I guess that 10w-40 is probably ok.
